Question Bank in DC Circuits

Question Bank in DC Circuits A. DC CIRCUITS: BASIC PRINCIPLES 1. REE Board Exam March 1998

The substation bus bar is made up of 2 inches round copper bars 20 ft long. What is the resistance of each bar if resistivity is 1.724 x 10

-6 ohm-cm.

A. 7.21 x 10-5

C. 5.185 x 10-5

B. 13.8 x 10

-6 D. 2.96 x 10

-5

2. REE October 1997

Determine the resistance of a busbar made of copper if the length is 10 meters long and the cross section is a 4 x 4 cm

2. Use 1.7241 micro ohm-cm as

the resistivity. A. 2.121 x 10

-4 C. 3.431 x 10

-5

B. 4.312 x 10-4

D. 1.078 x 10-4

3. EE Board Exam October 1991 One turn of a copper bar is produced by cutting copper washer along a radius and spreading the ends. The washer is cut from soft drawn copper having a resistivity at 20C of 1.732 x 10

-6 ohm-cm.

The washer is 0.125 inch thick and has inside diameter and outside diameter of 1 inch and 9 inches respectively. Calculate the exact resistance between the two ends of the turn to direct current, taking into account the non-uniform current distribution. Assume the contact along the ends of the turn to be perfect over the entire cross section.

A. 12.74 x 10-6

C. 17.22 x 10-6

B. 15.53 x 10

-6 D. 14.83 x 10

-6

4. EE Board Exam October 1990

Determine the resistance of a conductor 0.10 m long, with a uniform diameter of 1.0 cm and having a resistivity which varies as a function of length L measured from the one end of the conductor according to = 0.003 + 10

-4 L

2 ohm-cm.

A. 0.0852 ohm C. 0.0806 ohm B. 0.0915 ohm D. 0.0902 ohm 5. EE Board Exam April 1992

A coil has 6,000 turns of wire and a resistance of 380 ohms. The coil is rewound with the same quantity (weight) of wire, but has 13,400 turns. How many ohms will the new coil have?

A. 1895 ohms C. 1792 ohms B. 1825 ohms D. 1905 ohms 6. EE Board Exam April 1992

A copper wire of unknown length has a resistance of 0.80 ohm. By successive passes through drawing dies, the length of the wire is increased by 2 times its original value. Assuming that resistivity remains unchanged during the drawing process, determine the new value of its resistance.

A. 4 ohms C. 5 ohms B. 3 ohms D. 6 ohms

7. REE Board Exam October 1998 A one-meter rod of 2-cm diameter is drawn until its resistance is 100 times the initial resistance. Its length afterwards is?

A. 10 m C. 12.5 m B. 100 m D. 5 m 8. EE Board Exam April 1993

A kilometer of wire having a diameter of 11.7 mm and a resistance of 0.031 ohm is drawn down so that its diameter is 5.0 mm. What does its resistance become?

A. 0.85 ohm C. 0.93 ohm B. 0.78 ohm D. 0.81 ohm 9. EE Board Exam April 1995

A certain wire has a resistance R. The resistance of another wire identical with the first except for having twice its diameter is

A. 4R C. 2R B. R/2 D. R/4 10. REE Board Exam October 1996

What is the size in square millimeter (mm2) is the

cable of 250 MCM size? A. 118.656 mm

2 C. 112.565 mm

2

B. 126.675 mm2 D. 132.348 mm

2

11. REE Board Exam October 1998, September 2001

The resistance of a copper wire at 30C is 50 ohms. If the temperature coefficient of copper at 0C is 0.00427, what is the resistance at 100C?

A. 72.26 ohms C. 63.24 ohms B. 54.25 ohms D. 58.15 ohms 12. REE Board Exam March 1998

The resistance of a wire is 126.48 at 100C and 100 at 30C. Determine the temperature coefficient of copper at 0C.

A. 0.00427/C C. 0.0256/C B. 0.00615/C D. 0.365/C 13. EE Board Exam October 1991

Two heating elements which is 500 ohms and 250 ohms are connected in series with temperature coefficients of 0.001 and 0.003 ohms per C, respectively at 20C. Calculate the effective temperature coefficient of the combination.

A. 0.00215 C. 0.00712 B. 0.00626 D. 0.00167 14. EE Board Exam October 1992

The insulation resistance of a kilometer of the cable having a diameter of 2 cm and an insulation thickness of 2 cm is 600 ohms. If the thickness of the insulation is increased to 3 cm, find the insulation resistance of the cable.

A, 725 ohms C. 757 ohms B. 850 ohms D. 828 ohms 15. EE Board Exam April 1989

It is required that a loading of 3 kW be maintained in a heating element at an initial temperature of 20C,

a voltage of 220 V is necessary for the purpose. After the element has settled down to steady state, it is found that a voltage of 240 volts is necessary to maintain the 3 kW loading. The element resistance temperature coefficient is 0.0006 per degree centigrade at 20C. Calculate the final temperature of the heating element.

A. 345.43C C. 336.84C B. 326.42C D. 318.48C 16. REE Board Exam October 1999

How long must a current of 5 A pass through a 10 ohm resistor until a charge of 12000 coulomb passes through?

A. 1 min C. 3 min B. 2 min D. 4 min 17. REE Board Exam October 1999

What is the power required to transfer 97,000 coulombs of charge through a potential rise of 50 volts in one hour?

A. 0.5 kW C. 1.3 kW B. 0.9 kW D. 2.8 kW 18. REE Board Exam April 2001

A round wire has 250 MCM. Find its diameter in inches.

A. C. 0.16 B. D. 0.08 19. REE Board Exam September 2003

In the American wire gauge, as the number of gauge increases, the diameter of wire ____

A. increases B. decreases C. does not change D. become twice 20. REE Board Exam September 2003

In cgs system, what is the unit of emf where I is in abampere and P is in erg per second?

A. millivolt C. abvolt B. kilovolt D. volt 21. REE Board Exam September 2002 One (1) kW is equal to ____ hp. A. 0.746 C. 550 B. 1.34 D. 1.5 22. REE Board Exam October 1998

Two copper conductors have equal length. The cross-sectional area of one conductor is three times that of the other. If the resistance of the conductor having smaller cross-sectional area is 20 , what is the resistance of the other?

A. 20/3 C. 180 B. 60 D. 20/9 23. REE Board Exam October 2000

A copper bar has a length of 20 ft., width of 4 inches and thickness of 0.5 inch. If the resistivity of copper is 10.37 -CM/ft, what is the resistance of the bar?

A. 81.4 C. 814

B. 8.14 D. 0.814 24. REE Board Exam April 2001

The resistance of the field winding of a DC machine is 0.25 at 25C. When operating at full-load, the temperature of the winding is 75C. The temperature coefficient of resistance of copper is 0.00427 per C at 0C. Find the resistance of the field winding at full-load. A. 0.298 C. 0.512

B. 0.315 D. 0.271 25. REE Board Exam October 2000

A coil of copper has resistance of 5.46 at 75C. What will be its resistance at 25C?

A. 4.58 C. 5.02 B. 4.84 D. 4.35 26. REE Board Exam April 2001

A certain generator generates 1,500,000 joules per minute. What is the output in kW?

A. 50 C. 25 B. 500 D. 125 27. ECE BOARD NOV 2001

_____ is anything that has weight had occupies space. It may be solid, liquid or gas.

A. Amalgam C. Matter B. Alloy D. Compound 28. ECE Board Exam April 2000

It is defined as anything that occupies space and has weight.

A. atom C. molecule B. compound D. matter 29. ECE Board Exam November 1999 The lightest kind of atom or element A. hydrogen C. titanium B. helium D. oxygen 30. ECE Board Exam November 1998

In order to have a good conductor material, such material shall have _____ valence electrons.

A. one C. more than ten B. five D. twenty one 31. ECE Board Exam November 1997 Electric power refers to _____ A. volt ampere C. volt coulomb B. watt second D. joule 32. ECE Board Exam November 1995

What composes all matter whether a liquid, solid or gas?

A. electrons C. protons B. atoms D. neutrons 33. ECE Board Exam November 2001

What is a physical combination of compounds or elements NOT chemically combined that can be separated by physical means?

A. substance C. mixture

B. atom D. molecule 34. ECE Board Exam April 1998 Determine the equivalent work of 166 watt-second. A. 10 joules C. 16.6 joules B. 100 joules D. 166 joules 35. ECE Board Exam November 2001

One of the following is the best conductor of electricity.

A. Air C. Carbon B. Copper D. Silicon 36. ECE Board Exam November 1999 What is the basic unit for measuring current flow? A. coulomb C. volt B. ampere D. atomic weight 37. ECE Board Exam November 1995 ______ has a unit of electron volt A. Energy C. Current B. Potential difference D. Charge 38. ECE Board Exam November 2001

The motion of charged particles especially colloidal particles through a relative stationary liquid under the influence of an applied electric provided.

A. hysteresis C. electrophoresis B. electrolysis D. electro analysis 39. ECE Board Exam April 2001

What is a symbol that represents a quantity or a single object?

A. unit C. item B. number D. base 40. ECE Board Exam April 2000

Determine which of the following has the least number of electrons found at the outer shell.

A. semi-insulator C. semiconductor B. insulator D. conductor 41. ECE Board Exam April 2001

The term describes a material whose resistance remains relatively constant with changes in temperature

A. positive temperature coefficient B. negative temperature coefficient C. neutral temperature coefficient D. zero temperature coefficient 42. ECE Board Exam November 1998 Resulting effect when electron is made to move A. dynamic electricity C. lines of force B. static electricity D. magnetic lines 43. ECE Board Exam November 1997

One of the following characteristics of a resistive material which do not change its resistive value with respect to time is its _____

A. fidelity C. stability B. sensitivity D. selectivity

44. ECE Board Exam November 2001 What do you call the element that conducts electricity very readily?

A. semi-conductors C. insulators B. conductors D. dielectric 45. ECE Board Exam April 2001

Which of the following material is referred to as a medium whereby electrons can move easily from atom to atom?

A. insulator C. mica B. dielectric D. conductor 46. ECE Board Exam November 2001

A chemical combination of elements can be separated by chemical means but not by physical means. It is created by chemically combining two or more elements.

A. molecules C. matter B. compound D. mixture 47. ECE Board Exam April 2000

A substance which cannot be reduced to a simpler substance by chemical means

A. atom C. matter B. molecule D. element 48. ECE Board Exam November 2001

Calculate the equivalent power in watt of 100 joules per second.

A. 1.66 watts C. 16.66 watts B. 100 watts D. 1,000 watts 49. ECE Board Exam April 2001 It is a neutral particle that has no electrical charge. A. atom C. electron B. proton D. neutron 50. ECE Board Exam November 1999 Which material has more free electrons? A. mica C. conductor B. insulator D. dielectric 51. ECE Board Exam November 2001

The new and preferred term for conductance or mho

A. Siemens C. Seaman B. She-man D. ROM 52. ECE Board Exam April 2001

Represents the current flow produced by one volt working across one ohm of resistance.

A. resistance B. ampere C. voltage D. electromotive force 53. ECE Board Exam November 1995

When an atom gains an additional _____, it results to a negative ion.

A. atom C. proton B. neutron D. electron

54. ECE Board Exam November 1999 The definite discrete amount of energy required to move an electron from a lower shell to higher shell.

A. quantum B. positive energy C. negative energy D. quanta 55. ECE Board Exam November 1999

What will happen to an atom if an electron is either taken out or taken into the same atom?

A. becomes a negative ion B. becomes an ion C. becomes a positive ion D. nothing will happen 56. ECE Board Exam April 1999

The energy in an electron that is called the energy of motion

A. electromotive force B. kinematics C. kinetic energy D. potential energy 57. ECE Board Exam November 1996 Electric charge of neutron is the same as ______. A. atom C. current B. electron D. proton 58. ECE Board Exam April 1998 Ion is _____. A. free electron B. nucleus without protons C. proton D. an atom with unbalanced charges 59. ECE Board Exam November 1997

An insulating element or material has capability of _____.

A. storing voltage B. preventing short circuit between two

conducting wires C. conducting large current D. storing high current 60. ECE Board Exam April 1998

What is the value of a resistor with colors from left: Orange, Blue, Gold and Silver?

A. 34 ohms + /-10% B. 36 ohms +/-10% C. 3.4 ohms +/-10% D. 3.6 0hms +/-10% 61. ECE Board Exam April 2001

A three-terminal resistor with one or more sliding contacts which functions as an adjustable voltage divider

A. Rheostat C. Potentiometer B. Bleeder resistor D. Voltage divider 62. ECE Board Exam November 2000

A resistor which is used to draw a fixed amount of current

A. potentiometer C. fixed resistor B. bleeder resistor D. rheostat 63. ECE Board Exam November 2001

Find the value of a resistor with the following color codes: Orange, Yellow, Red, Red

A. 34 k ohms +/-5% B. 3.4 ohms +/-2% C. 3.4 k ohms +/-10% D. 34 k ohms +/-20% 64. ECE Board Exam November 1996 Electric energy refers to ______. A. Joules divided by time C. Watt B. Volt-ampere D. Volt-coulomb 65. ECE Board Exam April 2001 What is the resistance of an open fuse circuit? A. at least 1000 ohms B. infinity C. zero D. 100 ohms at standard temperature 66. ECE Board Exam April 1998

When should a fuse be replaced with a higher rated unit?

A. when the fuse of the original value is small in size

B. when the original is not available C. never D. if it blows 67. ECE Board Exam November 2000 The ability to do work A. energy C. potential B. kinetic D. voltage 68. ECE Board Exam November 2001

Which type of variable resistor should you use for controlling large amount of current?

A. Potentiometer C. Variac B. Adjustable wirewound D. Rheostat 69. ECE Board Exam April 2000

What does the fourth loop of an electronic resistor color code represent?

A. Multiplier B. Temperature C. First digit of the equivalent value D. Tolerance 70. ECE Board Exam November 2000 Ten micro-microfarads is equivalent to _____ A. 100 picofarads B. 100 nanofarad C. 1000 milli microfarad D. 10.0 picofarads 71. ECE Board Exam November 1995

How much is the resistance of a germanium slag 10 cm long and cross sectional area of 1 square cm?

A. 55 k ohms C. 550 k ohms B. 5.5 k ohms D. 550 ohms

72. ECE Board Exam November 2001

A variable resistor normally used as a voltage divider

A. Carbon film resistor B. Potentiometer C. Adjustable resistor D. Metal film resistor 73. ECE Board Exam April 2001

Determine the equivalent horse power of 2.611 kilowatts.

A. 3.50 hp C. 2.25 hp B. 2.50 hp D. 1.50 hp 74. ECE Board Exam November 2000

Find the lowest resistance value of the following resistors.

A. White, black, black B. Violet, gray, yellow, silver C. Red, black, gold D. Gray, gray, black 75. ECE Board Exam November 1998

If the bands on a resistor are yellow, violet, red and gold, what is the resistance value?

A. 470 ohms 5% B. 470 ohms 10% C. 47000 ohms 5% D. 4700 ohms 5% 76. ECE Board Exam November 1997

Rust in electrical (wire) connections will result to _____

A. Conductance C. Voltage B. Resistance D. Inductance 77. ECE Board Exam November 1996

The area of a conductor whose diameter is 0.001 inch is equal to

A. One micron C. One circular mil B. One angstrom D. One steradian 78. ECE Board Exam November 1995

_____ is the term used to express the amount of electrical energy in an electrostatic field.

A. Joule C. Volt B. Coulomb D. Watt 79. ECE Board Exam November 1995 Which of the following statement is correct? A. Potentiometer has two terminals B. Transistor has two terminals C. Typical power rating of a carbon-composition

resistor ranged from 0.125 W to 2 W D. Open resistor has small resistance 80. ECE Board Exam November 1996 _____ is one factor that does not affect resistance. A. Resistivity C. Length B. Cross sectional area D. Mass

81. ECE Board Exam November 1998 What is the value of a resistor having the following colored bands: Yellow-Gray-Red-Silver?

A. 4800 ohms 10% B. 480 ohms 10% C. 3800 ohms 1% D. 4.8 ohms 1% 82. ECE Board Exam November 1997

Find the value of resistor with the following color codes; Brown, White, Orange, Red

A. 190 ohms 10% B. 19 k ohms 2% C. 1.9 k ohms 10% D. 19 k ohms 20% 83. ECE Board Exam November 1998 Resistor with colored bands in the body A. Adjustable resistor B. Wire-wound resistor C. Variable resistor D. Carbon composition resistor 84. ECE Board Exam November 1998

If the bands on a resistor are red, red, orange and silver, what is the resistance value?

A. 220 ohms 5% B. 223 0hms 10% C. 22,000 ohms 10% D. 2200 ohms 20% 85. ECE Board Exam November 1997

What does the second strip of an electronic resistor color code represent?

A. Tolerance B. Second digit of the value C. Temperature D. Multiplier 86. ECE Board Exam November 2000

The energy in an electron that is called the energy of position

A. Kinetic energy B. Kinematics C. Electromotive force D. Potential energy 87. ECE Board Exam April 1999

If an electronic resistor does not have the fourth color strip it means it has a tolerance of _____.

A. 5% C. 10% B. 20% D. 1% 88. ECE Board Exam April 1998

What happens to the resistance of a conductor wire when its temperature is lowered?

A. Decreased C. Zero B. Steady D. Increased 89. ECE Board Exam April 1998

Which of the following does not refer to electric energy?

A. Joule C. Volt coulomb

B. Watt second D. Volt ampere 90. ECE Board Exam March 1996 Which of the following statement is incorrect? A. open transistor has three (3) terminals B. transistors have three (3) terminals C. typical power rating of carbon-composition

resistor ranged 0.001 W to 0.1 W D. potentiometer has three (3) terminals 91. ECE Board Exam November 1997

Term used in electronic measuring device when a metal increases resistance due to heat produced by current flowing through them.

A. positive resistance coefficient B. positive temperature coefficient C. negative temperature coefficient D. negative resistance coefficient 92. A 1 km cable consists of 12 identical strands of

aluminum each 3 mm in diameter. What is the resistance of the cable?

A. 0.34 ohm C. 0.44 ohm B. 0.54 ohm D. 0.24 ohm 93. A piece of wire has a resistance of 0.5 ohm. The

length is doubled and the area is increased four times. What is its resistance?

A. 0.75 ohm C. 0.25 ohm B. 0.50 ohm D. 1 ohm 94. Copper wire of certain length and resistance is

drawn out to four times its length without change in volume. What is the resistance of the bar?

A. unchanged C. 16R B. R/16 D. 4R 95. Current is simply _____. A. Flow of electrons C. Radiation B. Flow of protons D. Emission 96. The resistance of a coil of wire is 1 k at 20C. If

the coil is immersed into oil, the resistance falls to 880 . If the wire has a temperature coefficient of 0.006 at 20C, how much is the temperature of the liquid? A. 0C C. 17.6C B. -20C D. none of these

97. The copper field coils of a motor was measured at

21C and found to have a resistance of 68 . After the motor has run for a given time, the resistance is found to be 96 . What is the hot temperature of the winding?

A. 106.36C C. 103.66C B. 166.30C D. none of these 98. A wire has a resistance of 30 at 20C. What will

its resistance be at 60C? Assume the temperature coefficient of resistance to be 0.000385 at 20C.

A. 34.26 C. 32.46 B. 36.42 D. none of these

99. Determine the length of a copper wire ( = 10.37 -CM/ft) where diameter is 0.30 inch and resistance of 0.5 at 20C.

A. 4,339 ft C. 6,125 ft B. 5.225 ft D. none of these 100. An electric water heater has a rating of 1 kW, 230

V. The coil used as the heating element is 10 m long and has a resistivity of 1.724 x 10

-6 ohm-cm.

Determine the required diameter of the wire in mils. A. 2.43 mils C. 3.21 mils B. 2.52 mils D. 1.35 mils 101. A certain wire 20 ft long and 100 circular mil area

has a resistance of 1.6 . What is its resistivity? A. 10.3 ohm-CM/ft B. 2.2 ohm-CM/ft C. 8 ohm-CM/ft D. 15.2 ohm-CM/ft 102. How many circular mils does a round copper rod of

0.25 inch diameter have? A. 196,000 C. 1,963,500 B. 62,500 D. 49,000 103. A substance whose molecules consist of the same

kind of atoms is called ____. A. mixture B. element C. compound D. none of the above 104. The diameter of the atom is about ____. A. 10

-10 m C. 10

-2 m

B. 10-8

m D. 10-15

m 105. The number of compounds available in nature is

____. A. 105 C. 1000 B. 300 D. unlimited 106. The mass of a proton is ____ the mass of an

electron. A. equal to B. less than C. about 1837 times D. 200 times 107. The maximum number of electrons that can be

accommodated in the last orbit is ____. A. 4 C. 18 B. 8 D. 2 108. The electrons in the last orbit of an atom are called

____ electrons. A. free C. valence B. bound D. thermionic 109. If the number of valence electrons of an atom is

less than 4, the substance is usually ____. A. a conductor B. an insulator C. a semiconductor

D. none of the above 110. If the number of valence electrons of an atom is

more than 4, the substance is usually ____. A. a semiconductor B. a conductor C. an insulator D. none of the above 111. If the number of valence electrons of an atom is

exactly 4, the substance is usually ____. A. a semiconductor B. an insulator C. a conductor D. a semiconductor 112. The number of valence electrons of an atom is less

than 4. The substance will be probably ____. A. a metal B. a non-metal C. an insulator D. a semiconductor 113. One coulomb of charge is equal to the charge on

____ electrons. A. 628 x 10

16 C. 62.8 x 10

16

B. 6.28 x 1016

D. 0.628 x 1016

114. One cc of copper has about ____ free electrons at

room temperature. A. 200 C. 8.5 x 10

22

B. 20 x 1010

D. 3 x 105

115. Electric current in a wire is the flow of ____. A. free electrons B. bound electrons C. valence electrons D. atoms 116. EMF in a circuit is ____. A. cause current to flow B. maintains potential difference C. increases the circuit resistance D. none of these 117. EMF has the unit of _____. A. power C. charge B. energy D. none of these 118. Potential difference has the unit of ____ . A. charge B. power C. energy D. none of the above 119. The resistance of a material is ____ its area of

cross-section. A. directly proportional to B. inversely proportional to C. independent of D. none of the above

120. If the length and area of cross-section of a wire are doubled up, then its resistance ____.

A. becomes four times B. remains unchanged C. becomes sixteen times D. none of the above 121. A length of wire has a resistance of 6 ohms. The

resistance of a wire of the same material three times as long and twice the cross-sectional area will be ____.

A. 36 ohms C. 9 ohms B. 12 ohms D. 1 ohm 122. The SI unit of specific resistance is ____. A. mho C. ohm-m

2

B. ohm-m D. ohm-cm 123. The specific resistance of a conductor ____ with

rise in temperature. A. increases B. decreases C. remains unchanged D. none of the above 124. The SI unit of conductivity is ____. A. ohm-m C. mho-m B. ohm/m D. mho/m 125. The SI unit of conductance is ____. A. mho C. ohm-m B. ohm D. ohm-cm 126. The resistance of a material 2 m long and 2 m

2 in

cross-sectional area is 1.6 x 10-8

. Its specific resistance will be ____.

A. 3.2 x 10-8

ohm-m B. 6.4 x 10

-8 ohm-m

C. 1.6 x 10-8

ohm-m D. 0.16 x 10

-8 ohm-m

127. Conductors have ____ temperature coefficient of

resistance. A. positive B. negative C. zero D. none of the above 128. Semiconductors have ____ temperature coefficient

of resistance. A. negative B. positive C. zero D. none of the above 129. The value of (i.e. temperature coefficient of

resistance) depends upon A. length of the material B. cross-sectional area of the material C. volume of the material D. nature of the material and temperature

130. The temperature coefficient of resistance of a conductor ____ with rise in temperature.

A. increases B. decreases C. remains unchanged D. none of the above 131. Insulators have ____ temperature coefficient of

resistance. A. zero B. positive C. negative D. none of the above 132. Eureka has ____ temperature coefficient of

resistance. A. positive B. negative C. almost zero D. none of the above 133. Fig. 1.1 shows the temperature/resistance graph of

a conductor. The value of 0 is ____.

50

50C

40

Temperaturet

Res

ista

nce

()

Fig. 1.1 A. 0.005/C C. 0.1/C B. 0.004/C D. 0.4/C 134. Referring to Fig. 1.1, the value of the 50 will be

____.

50

50C

40

Temperaturet

Res

ista

nce

()

Fig. 1.1 A. 0.005/C C. 0.1/C B. 0.004/C D. 0.4/C 135. Referring to Fig. 1.2, the value of 0 is ____. A. 1/30 per C B. 1/40 per C C. 1/1200 per C D. none of the above 136. Referring to Fig. 1.2, the value of R40 will be ____.

40C

20

Temperaturet

Res

ista

nce

()

Fig. 1.2

45

A. 70 ohms C. 35 ohms B. 40 ohms D. 50 ohms 137. Referring to Fig. 1.2, the value of 40 will be ____.

40C

20

Temperaturet

Res

ista

nce

()

Fig. 1.2

45

A. 1/30 per C C. 1/50 per C B. 1/70 per C D. 1/1200 per C 138. The value of 0 of a conductor is 1/236 per C. The

value of 18 will be ____. A. 1/218 per C B. 1/272 per C C. 1/254 per C D. none of the above 139. The value of 50 of a conductor is 1/230 per C. The

value of 0 will be ____. A. 1/180 per C B. 1/280 per C C. 1/250 per C

D. none of the above 140. A good electric conductor is one that A. has low conductance B. is always made of copper wire C. produces a minimum voltage drop D. has few free electrons 141. Two wires A and B have the same cross-section

and are made of the same material, RA = 600 and RB = 100 . The number of times A is longer than B is

A. 6 C. 4 B. 2 D. 5

142. A coil has a resistance of 100 at 90C. At 100C, its resistance is 101 . The temperature coefficient of wire at 90C is

A. 0.01 C. 0.0001 B. 0.1 D. 0.001 143. Which of the following material has nearly zero

temperature-coefficient of resistance? A. carbon C. copper

B. porcelain D. manganin 144. Which of the following material has a negative

temperature coefficient of resistance? A. brass C. aluminum B. copper D. carbon 145. A cylindrical wire 1 m in length, has a resistance of

100 . What would be the resistance of a wire made from the same material both the length and the cross-sectional area are doubled?

A. 200 C. 100 B. 400 D. 50 146. Carbon composition resistors are most popular

because they A. cost the least B. are smaller C. can withstand overload D. do not produce electric noise

147. A unique feature of a wire-wound resistor is its A. lower power rating C. high stability B. low cost D. small size 148. A coil has a resistance of 100 ohms at 90

C. At

100C, its resistance is 101 ohms. What is the temperature coefficient of the wire at 90

C?

A. 0.01 C. 0.0001 B. 0.1 D. 0.001 149. What is the unit for charge (Q)? A. Farad C. Siemens B. Joule D. Coulomb 150. The charge delivered by a constant voltage source

is shown. Determine the current supplied by the source at (a) t = 1 s (b) t = 3 s.

A. 5 ma, -3.33 ma C. 3.33 ma, 5 ma B. 5 ma, 3.33 ma D. 3.33 ma, 5 ma B. OHMS LAW AND ELECTRIC CIRCUITS 151. REE Board Exam October 1998

The resistance of 120 meters of wire is 12 ohms. What is its conductance?

A. 0.0521 siemens C. 6 siemens B. 0.0833 siemens D. 12 siemens 152. EE April 1981, October 1984

Two (2) 115-V incandescent lamps A and B are connected in series across a 230-V source. If lamp A is rated 75 watts and lamp B is rated 50 watts, determine the current drawn by the series connection.

A. 0.52 A C. 0.48 A B. 0.64 A D. 0.57 A

153. REE Board Exam March 1998 Three resistors of 10, 15 and 20 ohms each are connected in parallel. What is the equivalent resistance?

A. 45 ohms C. 0.22 ohm B. 17.2 ohms D. 4.62 ohms 154. REE Board Exam March 1998

Three resistors of 10, 15 and 20 ohms each are connected in parallel. What is the total conductance?

A. 0.217 siemens C. 4.52 siemens B. 3.41 siemens D. 0.562 siemens 155. REE Board Exam October 1997

A 5-ohm resistance is connected in parallel with a 10-ohm resistance. Another set, a 6-ohm and an 8-ohm resistances are also connected in parallel. The two sets are connected in series. What is the equivalent resistance?

A. 6.76 ohm C. 14.4 ohms B. 9.25 ohm D. 21.2 ohms 156. REE Board Exam March 1998

Two resistances of 10 and 15 ohms each respectively are connected in parallel. The two are then connected in series with a 5-ohm resistance. What is the equivalent resistance?

A. 11 ohms C. 10 ohms B. 12 ohms D. 9 ohms 157. REE Board Exam October 1997

A 10-ohm and a 20-ohm resistance are connected in parallel. Another resistance of 5-ohm is connected in series with the two. If the supply voltage is 48 volts, what is the current through the 10-ohm resistor?

A. 3.21 A C. 4.02 A B. 2.74 A D. 5.72 A 158. REE Board Exam March 1998

Two resistances of 10 and 15 ohms, each respectively are connected in parallel. The two are then connected in series with a 5-ohm resistance. It is then connected across a 12-V battery, what are the current and power?

A. 1.2 A, 17.28 W C. 1.09 A, 13.1 W B. 0.96 A, 11.52 W D. 1.5 A, 20.25 W 159. REE Board Exam September 2001

Three resistors 10-, 15- and 20- are connected in series across a 48-V source. What is the voltage across the 15- resistor?

A. 20 V C. 24 V B. 16 V D. 12 V 160. REE Board Exam September 2001

Three resistors 10-, 15- and 20- are connected in parallel. What is the total resistance?

A. 3.56 C. 0.217 B. 4.62 D. 45

161. REE Board Exam September 2000 Two 10- resistances are connected in parallel. The two are then connected in series with a 5- resistance. It is then connected across a 24-volt battery; find the voltage across the 5- resistor.

A. 12 volts C. 9 volts B. 24 volts D. 15 volts 162. REE Board Exam April 1997

A circuit consists of three resistors rated 3-, 4- and 5- connected in parallel. If the circuit is connected to a battery which has an internal resistance of 0.2-, what would be the current through the 4- resistor?

A. 2.04 A C. 2.4 A B. 4.8 A D. 3.0 A 163. REE Board Exam September 2000 How many abvolts in 1 volt? A. 10

8 abvolts C. 1 abvolt

B. 10-8

abvolts D. 10 abvolt 164. REE Board Exam September 2003

A total current of 60 A is divided among 3 parallel branches having resistances of 10 , 6 and 12 , respectively. What is the current that flows through the branch with 10 resistance?

A. 17.1 A C. 14.3 A B. 28.6 A D. 42.9 A 165. REE Board Exam October 2000

Two 10-ohm parallel resistors are connected in series with a 5-ohm resistor. The combination is then connected across a 24 volts battery. Find the voltage drop across the 5-ohm resistor.

A. 6 V C. 12 V B. 18 V D. 20 V 166. ECE Board Exam November 1998

The theory of Ohms law is applied in a _____ circuit.

A. linear C. trivalent B. exponential D. unilateral 167. ECE Board Exam April 2000

Refers to the most important components in controlling flow of electrons

A. voltage, electromotive force and current B. reactance, current and resistance C. conductance, resistance and reactance D. voltage, resistance and current 168. ECE Board Exam November 1999

Which of the following is not a valid expression of ohms law?

A. E = IR C. R = E/I B. R = PI D. I = E/R 169. ECE Board Exam November 2000

A simple electronic equipment which takes a 2 amperes current from a power source has a total load resistance of 100 ohms. How much power does it use?

A. 200 watts C. 400 watts B. 100 watts D. 50 watts 170. ECE Board Exam November 1996

What do you expect when you use the two 20 kohms, 1 watt resistor in parallel instead of one 10 kohms, 1 watt?

A. Provide lighter current B. Provide wider tolerance C. Provide more power D. Provide less power 171. ECE Board Exam November 1999

The total resistance of a two similar wire conductors connected in parallel is ______

A. same resistance of one wire B. double the resistance of one wire C. one half the resistance of one wire D. resistance of one wire multiplied by 4 172. ECE Board Exam March 1996

When you increase the resistance in a circuit, the flow of electrons will ______.

A. be constant C. be stopped B. flow faster D. be decreased 173. ECE Board Exam April 2001

Which of the following allows more current if applied to the same voltage?

A. 0.002 siemen C. 0.004 siemen B. 25 ohms D. 2.5 ohms 174. ECE Board Exam April 1998 Ohms law refers to _____. A. power is directly proportional to both voltage

squared and the resistance B. power is directly proportional to the resistance

and inversely as the current squared C. current varies directly as the voltage and

inversely as the resistance D. current is directly proportional to both voltage

and resistance 175. ECE Board Exam November 2000

A circuit which a break exists in the complete conduction pathway

A. Open circuit C. Close circuit B. Short circuit D. Circuit 176. ECE Board Exam November 1997

How much is the equivalent power in watts can a 3 horse power provide?

A. 3000 watts C. 1492 watts B. 248.66 watts D. 2238 watts 177. ECE Board Exam March 1996

The current needed to operate a soldering iron which has a rating of 600 watts at 110 volts is

A. 18,200 A C. 66,000 A B. 0.182 A D. 5.455 A


Find the power across the resistor of 5 ohms delivered from a battery of an internal resistance of 3 ohms and a constant emf of 4 volts.

A. 120 watts C. 60 watts B. 100 watts D. 1.25 watts 179. ECE Board Exam April 2000

A series circuit in which desired portions of the source voltage may be tapped off for use equipment.

A. Voltage trap B. Voltage selector C. Voltage divider D. Dividing network 180. ECE Board Exam April 1998

An electronic device draws 300 watts from its 24 volt power source. Find effective resistance.

A. 1.25 C. 19.20 B. 1.92 D. 12.50 181. ECE Board Exam November 1997

How much power does an electronic equipment consume, assuming a 5.50 amperes current flowing and a 120 volts power source?

A. 125.5 watts C. 660 watts B. 66 watts D. 60 watts 182. ECE Board Exam March 1996

What type of circuit whose parameters are constant which do not change with voltage or current?

A. Tuned circuit C. Reactive circuit B. Linear circuit D. Lumped circuit 183. ECE Board Exam April 2000

If three circuits, each with a value of 560 ohms are connected in parallel, what is the total resistance of the combination?

A. 1680 ohms C. 18567 ohms B. 560 ohms D. 187 0hms 184. ECE Board Exam November 1997

Other factors remaining constant, what would be the effect on the current flow in a given circuit if the applied potential were doubled?

A. It would double B. It would increase 4 times C. It would remain the same D. It would be decrease by 185. ECE Board Exam April 1999

Find used power of a circuit whose power source supplies 20 volts and a load resistance of 200 ohms.

A. 1 watt C. 10 watts B. 4 kilowatts D. 2 watts 186. ECE Board Exam April 1998

When resistors are connected in series, what happens?

A. Nothing

B. The tolerance is decreased C. The effective resistance is decreased D. The effective resistance is increased 187. ECE Board Exam November 1999

A condition in which the heat in of around the circuit increases beyond or to a higher than normal level.

A. Excessive heat condition B. Open condition C. Direct short D. Grounded 188. ECE Board Exam November 1999

A 33 kilo ohms resistor is connected in a series parallel combination made up of a 56 kilo ohm resistor and a 7.8 kilo ohm resistor. What is the total combined resistance of these three resistors?

A. 39067 ohms C. 63769 ohms B. 49069 ohms D. 95800 ohms 189. ECE Board Exam April 2001

If 3,300 ohms resistor and a 22,000 ohms resistor are connected in series, what is the total resistance?

A. 18,700 ohms C. 5,500 ohms B. 25,300 ohms D. 2,870 ohms 190. ECE Board Exam November 2000 A device that draws current A. Source C. Load B. No load D. Shunt 191. ECE Board Exam April 1998

With the same voltage applied which of the following allows more current?

A. 25 ohms C. 2.5 ohms B. 250 ohms D. 0.25 ohms 192. ECE Board Exam April 1998

If 12 V are applied to a circuit that consumes 78 W, what is the current flow through the circuits?

A. 6.5 A C. 0.15 A B. 936 A D. 9.36 A 193. ECE Board Exam April 1998

Find the current that flows through the filament of a 400 watt flat iron connected to a 220 volt power line.

A. 50 mA C. 5 mA B. 500 mA D. 5 A 194. Four equal resistances are connected in parallel

across a certain supply producing P power. How much power will be produced if the resistances are now connected in series across the same supply?

A. 16P C. 4P B. P/16 D. P/4 195. A resistor R is connected across a 120 V supply. A

voltmeter of 10,000 ohms resistance is connected between the center of the resistor and one side of the supply and reads 40 V. What is the value of the resistance R?

A. 10,000 C. 30,000

B. 20,000 D. 196. A 240 V motor requiring 2,000 W is located 1 km

from a power source. What diameter of copper wire is to be used if the power loss is to be kept 5%?

A. 0.49 cm C. 0.39 cm B. 0.54 cm D. 0.35 cm 197. Three resistors of 10, 12 and x ohms, respectively

are connected in parallel across a constant current source of 8 A. Determine x if this resistor draws 2.5 A.

A. 10 C. 13 B. 12 D. 11 198. An arc lamp takes 10 A at 50 volts. A resistance R

is to be place in series so that the lamp my burn correctly from a 110 V supply. Find the power wasted in this resistor.

A. 800 watts C. 700 watts B. 600 watts D. 900 watts

199. A 20 and 10 resistors are connected in parallel

and a 5 resistor is connected in series with the parallel combination. The circuit is connected across a 48 V source with an internal resistance of

0.2 . Calculate the current through the 5 resistor.

A. 5.57 amperes C. 3.58 amperes B. 4.04 amperes D. 7.63 amperes 200. A variable resistor R is connected in parallel with a

fixed resistor of 1.25 ohms. The combination is then connected across a 12 V battery with internal resistance of 0.25 . Solve for the maximum power that can delivered to R.

A. 130.20 W C. 120.21 W B. 115.52 W D. 142.42 W 201. The hot resistance of an incandescent lamp is 10

ohms and the rated voltage is 50 V. Find the series resistance required to operate the lamp from an 80 V supply.

A. 8 C. 6

B. 4 D. 10 202. Ohms law is not applicable to A. copper B. silver C. silicon carbide D. aluminum 203. The practical unit of electrical energy is A. watt B. kilowatt C. kilowatt-hour D. megawatt 204. A 100 watt lamp working for 20 hours will consume

____ units. A. 200 C. 2 B. 20 D. 5

205. The hot resistance of an incandescent lamp is about ____ its cold resistance.

A. 10 times C. 100 times B. 2 times D. 50 times 206. A d.c. circuit usually has ____ as the load. A. resistance B. inductance C. capacitance D. both inductance and capacitance 207. The purpose of load in an electric circuit is to ____. A. increase the circuit current B. utilize electrical energy C. decrease the circuit current D. none of the above 208. Electrical appliances are not connected in series

because ____ A. series circuit is complicated B. appliances have different current rating C. power loss is more D. none of the above 209. Electrical appliances are connected in parallel

because it ____ A. is a simple circuit B. draws less current C. results in reduce in power loss D. makes the operation of appliances independent

of each other 210. Inductance and capacitance are not relevant in a

d.c. circuit because ____ A. frequency of d.c. is zero B. it is a simple circuit C. they do not exist in a d.c. circuit D. none of the above 211. The hot resistance of a 100 watt, 250 V

incandescent lamp would be A. 2.5 ohms B. 625 ohms C. 25 ohms D. none of the above 212. The voltage drop across 14.5 ohm resistor in Fig.

2.1 is ____.

14.5 25.5 60

200 V+ -

Fig. 2.1

A. 29 V C. 30.5 V B. 14 V D. 18 V

213. The circuit shown in Fig. 2.1 is called a series circuit

because ____

14.5 25.5 60

200 V+ -

Fig. 2.1

A. it contains a few resistances B. it carries the same current throughout the

circuit C. it is a simple circuit D. none of the above Referring to Fig. 2.2, the total circuit resistance will be ____ 214.

-+

100 W, 200 V 40 W, 200 V

Lamp A Lamp B

200 V

Fig. 2.2

A. 1000 ohms C. 1400 ohms B. 400 ohms D. 135 ohms 215. In Fig. 2.2 ____

-+

100 W, 200 V 40 W, 200 V

Lamp A Lamp B

200 V

Fig. 2.2

A. the lamp A will be brighter than lamp B B. the lamp B will be brighter than lamp A C. the two lamps will be equally bright D. none of the above 216. When a number of resistances are connected in

parallel, the total resistance is ____ A. less than the smaller resistance B. greater than the smaller resistance C. between the smaller and greatest resistance D. none of the above 217. Two resistances of 6 ohms and 3 ohms are

connected in parallel. The total resistance is ____ A. 9 ohms C. 0.5 ohm B. 18 ohms D. 2 ohms 218. The value of R that will give a total resistance of 1.5

ohms in Fig. 2.3 is ____

3

R

Fig. 2.3


219. The current in 2.5 ohm resistor in Fig. 2.4 will be

____

Fig. 2.4

2.5

4.5

7 A

A. 3 A C. 2.5 A B. 4.5 A D. 2 A 220. The current in 4.5 ohms resistor in Fig. 1.4 will be

____.

Fig. 2.4

2.5

4.5

7 A

A. 3.5 A C. 2 A B. 3 A D. 2.5 A 221. If 18 resistances, each of value 36 ohms, are

connected in parallel, then the total resistance is ____

A. 2 ohms B. 54 ohms C. 36 ohms D. none of the above 222. Two incandescent lamps of 100 W, 200 V are in

parallel across 200 V supply. The total resistance will be ____.

A. 800 ohms C. 400 ohms B. 200 ohms D. 600 ohms 223. The resistance across the terminals AB of the circuit

shown in Fig. 2.5 is ____

Fig. 2.5

18 12

A

B

6 C

A. 36 ohms C. 9 ohms B. 18 ohms D. 15 ohms 224. If a d.c. supply of 180 V is connected across

terminals AB in Fig. 2.5, then current in 6 ohm resistor will be ____.

Fig. 2.5

18 12

A

B

6 C

A. 10 A C. 12 A B. 5 A D. 6 A 225. The resistance across terminals AC in Fig. 2.5 is

____

Fig. 2.5

18 12

A

B

6 C

A. 36 ohms C. 18 ohms B. 9 ohms D. 8 ohms 226. The resistance across terminals AB of the circuit

shown in Fig. 2.6 is ____

Fig. 2.6

5 2

8 6 4

A

B


227. If a battery of 24 V is applied across terminals AB of

the circuit shown in Fig. 2.6, then current in 2 ohm resistor will be ____

Fig. 2.6

5 2

8 6 4

A

B

A. 3 A C. 2.5 A B. 6 A D. 1.5 A 228. If a battery of 24 V is applied across terminals AB in

Fig. 2.6, then power loss in 5 ohms resistor will be ____

Fig. 2.6

5 2

8 6 4

A

B

A. 180 W C. 90 W B. 45 W D. 24 W 229. The total conductance of the circuit shown in Fig.

2.7 is ____

Fig. 2.7

10 2 1

A. 13 mhos C. 6 mhos B. 1.6 mhos D. 2.5 mhos 230. If 10 ohms resistance is removed in Fig. 2.7, then

total conductance of the circuit will be ____

Fig. 2.7

10 2 1

A. 3 mhos C. 2 mhos B. 6 mhos D. 1.5 mhos

231. The voltage across the parallel circuit shown in Fig.

2.8 is ____

Fig. 2.8

15 A 10

2.5

2

A. 15 V C. 30 V B. 10 V D. 12. 5 V

232. The current in 10 ohms resistor in Fig. 2.8 is ____

Fig. 2.8

15 A 10

2.5

2

A. 3 A C. 1.5 A B. 2.5 A D. 3.5 A 233. The total resistance between terminals 1 and 2 of

the circuit shown in Fig. 2.9 is ____

Fig. 2.9

2 2

4 1 2

A. 12 ohms C. 2 ohms B. 2.67 ohms D. 64 ohms

234. If a battery of 12 V is applied across terminals 1 and

2 of Fig. 1.9, then current through 4 ohms resistor will be ____

Fig. 1.9

2 2

4 1 2

A. 1.5 A C. 2 A B. 3 A D. 2.5 A 235. The resistance between terminals 1 and 2 of Fig.

1.10 is ____

Fig. 1.10

2

6 1 2

2 2

A. 12 ohms C. 16 ohms B. 8 ohms D. 3 ohms 236. The resistance between terminals 1 and 2 in Fig.

1.11 is ____

Fig. 1.11

2

1

1 2

1 2

1

A. 2 ohms C. 1 ohm B. 1.5 ohms D. 4 ohms 237. If a battery of 6 V is applied across terminals 1 and

2 in Fig. 1.11, then current in the horizontal 2 ohm resistor will be ____

Fig. 1.11

2

1

1 2

1 2

1

A. 1 A C. 3 A B. 2 A D. 0.5 A 238. The resistance across terminals 1 and 2 in Fig. 1.12

is ____

2 1 2

1 2

1


239. Two equal resistances are connected in series across a certain supply. If the resistances are now connected in parallel across the same supply, the power produced will be ____ that of series connection.

A. two times C. one-half B. four times D. one-fourth 240. Referring to Fig. 1.13, the resistance across

terminals BE is ____

Fig. 1.13

72

13

14

6

9

18

11

44 V

A B C

DF E

A. 9 ohms B. 18 ohms C. 10 ohms D. none of the above 241. Referring to Fig. 1.13, the resistance across

terminals AF is ____

Fig. 1.13

72

13

14

6

9

18

11

44 V

A B C

DF E

A. 20.5 ohms B. 18 ohms C. 11 ohms D. none of the above 242. Referring to Fig. 1.13, the current in 18 ohms

resistor will be ___

Fig. 1.13

72

13

14 6

9

18

11

44 V

A B C

DF E

A. 2 A B. 1.5 A C. 1 A D. none of the above 243. Referring to Fig. 1.13, the power loss in 11 ohms

will be ____

Fig. 1.13

72

13

14

6

9

18

11

44 V

A B C

DF E

A. 11 W B. 24 W C. 16 W D. none of the above 244. If in Fig. 1.14, switches S1 and S2 are closed, then

total circuit resistance is ____

100 W, 200 V

200 V

Fig. 1.14

L3

L2

100 W, 200 V

40 W, 200 V

L1

+ -

S1

S2


245. If switch S1 is open and switch S2 is closed in Fig.

1.14, then circuit resistance will be ____

100 W, 200 V

200 V

Fig. 1.14

L3

L2

100 W, 200 V

40 W, 200 V

L1

+ -

S1

S2

A. 1200 ohms C. 1400 ohms B. 1000 ohms D. 2400 ohms 246. If in Fig. 1.14, both switches S1 and S2 are closed,

then ____ 100 W, 200 V

200 V

Fig. 1.14

L3

L2

100 W, 200 V

40 W, 200 V

L1

+ -

S1

S2

A. L1 will be brighter than L2 or L3 B. L1 will be dimmer than L2 or L3 C. L1 will be as bright as L2 or L3 D. none of the above 247. If in Fig. 1.14 switches S1 and S2 are open, then

lamp L1 will give output ____

100 W, 200 V

200 V

Fig. 1.14

L3

L2

100 W, 200 V

40 W, 200 V

L1

+ -

S1

S2

A. less than 40 W B. more than 40 W C. equal to 40 W D. none of the above 248. If in Fig. 1.14 switches S1 and S2 are closed and the

supply voltage is increased to 400 V, then ____

100 W, 200 V

200 V

Fig. 1.14

L3

L2

100 W, 200 V

40 W, 200 V

L1

+ -

S1

S2

A. lamp L1 will burn out B. lamp L2 will burn out C. both lamps L2 and L3 will burn out D. all the lamps will be safe 249. If in Fig. 1.1, resistor R2 becomes open-circuited,

the reading of the voltmeter will become

V

R2

200 V

R4R3R1

20 20 20 20

Figure 1.1

A. zero C. 50 V B. 150 V D. 200 V 250. Whatever the battery voltage in Fig. 1.2, it is certain

that smallest current will flow in the resistance of ____ ohm.

300

200

100 500

Figure 1.2

A. 300 C. 200 B. 500 D. 100

251. Which of the following statement is TRUE both for a

series and parallel d.c circuit? A. powers are additive B. voltages are additive C. current additive D. elements have individual currents

252. A 100-W, 110-V and a 50-W lamp are connected in

series across a 220-V dc source. If the resistances of the two lamps are assumed to remain constant, the voltage across the 100-W lamp is ____ volt.

A. 110 C. 146.7 B. 73.3 D. 220 253. In the parallel circuit of Fig.1.3, the value of V0 is

____ volt. 2

2

12 V12 V

VO

Figure 1.3

A. 12 C. 0 B. 24 D. -12 254. In the series circuit of Fig 1.4, the value of V0 is

____ volt. 2

2 12 V

VO

Figure 1.4

A. 12 C. 0 B. -12 D. 6 255. In Fig 1.5, there is a drop of 20 V on each resistor.

The potential of point A would be ____ volt.

BA

CD

80 V G

Figure 1.5

A. +80 C. +40 B. -40 D. -80 256. From the voltmeter reading of Fig. 1.6, is it obvious

that

3 24 V 6

4

Figure 1.6

A. the 3 resistor is short circuited

B. the 6 resistor is short circuited C. nothing is wrong with the circuit

D. the 3 resistor is open-circuited 257. With reference to Fig 1.7, which of the following

statement is true?

R1

R2E

R3

Figure 1.7

A. E and R1 form a series circuit B. R1 is in series with R3 C. R1 is in series with R2 D. there is no series circuit

258. Which of the following statements is correct

concerning the Fig. 1.8?

R1

R2

E R3

Figure 1.8

A. R2 and R3 form a series of path B. E is in series with R1 C. R1 is in parallel in R3 D. R1, R2 and R3 form a series of circuit

259. What is the equivalent resistance in ohms between

points A and B of Fig. 1.9? All resistances are in ohms

12

4

6

A

B

Figure 1.9

A. 12 C. 22 B. 14.4 D. 2 260. What do you call a resistor that does not obey

Ohms Law? A. Potentiometer B. Carbon-Film Resistor C. Wire-Wound Type

D. Non-linear Resistor 261. A 100 W, 110 V and 50 W, 110 V lamps are

connected in series across a 220 V DC source. If the resistances of the two lamps are assumed to remain constant, the voltage across the 100 W lamp is _____ volt?

A. 110 V C. 146.7 V B. 73.3 V D. 220 V 262. A potential divider of resistance of 50 ohms is

connected across a 100 V DC source. A load resistance of 10 ohms is connected across a tap in the potential divider and the negative terminal of the source. If a current of 4 A flows towards the load, what is the current supplied by the source?

A. 5.32 A C. 5.21 A B. 5.05 A D. 5.48 A 263. Two resistors A and B made of different materials

have temperature coefficients of resistance at 20C of 0.004 and 0.006 respectively. When connected

across a voltage source at 20C, they draw current equally. What percentage of the total current at

100C does resistor A carry? A. 47.14% C. 61.34% B. 52.86% D. 38.66%

264. A conductor has a resistance of 7 ohms at 0C. At

20C, the resistance has become 7.5 ohms. Calculate the temperature coefficient of the

conductor at 20C. A. 1/300 /C C. 1/500 /C B. 1/400 /C D. 1/600 /C 265. Which of the following is a non-linear element? A. diode B. heater coil C. transistor D. electric arc with unlike electrode

C. ELECTRICAL AND HEAT ENERGY 266. EE Board Exam April 1992

An electric kettle was marked 500 W, 230 V found to take 15 minutes to bring 1 kilogram of water at 15C to boiling point. Determine the heat efficiency of the kettle.

A. 79.1% C. 72.4% B. 75.3% D. 74.8% 267. REE Board Exam October 1997

A process equipment contains 100 gallons of water at 25C. It is required to bring it to boiling in 10 minutes. The heat loss is estimated to be 5%. What is the kW rating of the heater?

A. 125 kW C. 50.5 kW B. 252 kW D. 207 kW 268. EE October 1989

A total of 0.8 kg of water at 20C is placed in a 1-kW electric kettle. How long a time in minute is needed to raise the temperature of the water to 100C?

A. 4.46 min C. 5.34 min

B. 5.32 min D. 4,.56 min

269. REE October 1998 How many calories does an electric heater of 100 watts generate per second?

A. 10 C. 23.88 B. 1000 D. 42.25

270. REE Board Exam October 1997

The electric energy required to raise the temperature of water in a pool is 1000 kWh. If the heat losses are 25%, the heating energy required will be ____.

A. 1111 kWh C. 1750 kWh B. 1266 kWh D. 1333 kWh 271. EE Board Exam April 1992

An electric heater carries 12 A at 110 V, is submerged in 22.5 lbs of water for 30 minutes. What will be the final temperature of the water if its initial temperature is 35F?

A. 135.43F C. 133.56F B. 125.42F D. 128.33F 272. EE Board Exam October 1990

In an electric heater the inlet temperature is 15C. Water is flowing at the rate of 300 grams per minute. The voltmeter measuring voltage across the heating element reads 120 volts and an ammeter measuring current taken reads 10 amperes. When steady state is finally reached, what is the final reading of the outlet thermometer?

A. 57.6C C. 72.6C B. 68.4C D. 42.6C 273. EE Board Exam October 1991

Four cubic meters of water is to be heated by means of four 1.5 kW, 230-V immersion heating elements. Assuming the efficiency of the heater as 90%, determine the time required in boiling the water if the initial temperature is 20C and if all four elements are connected in parallel.

A. 71 hrs C. 69 hrs B. 63 hrs D. 66 hrs 274. EE Board Exam October 1991

Four cubic meters of water is to be heated by means of four 1.5 kW, 230-V immersion heating elements. Assuming the efficiency of the heater as 90%, determine the time required in boiling the water if the initial temperature is 20C and if the elements are connected two in series in parallel with two in series.

A. 275.6 hrs C. 252.2 hrs B. 295.3 hrs D. 264.4 hrs 275. REE Board Exam September 2001 How many joules per second are then in 10 watts? A. 10 C. 20 B. 5 D. 24.5 276. REE Board Exam September 2001 10

13 ergs/sec is equal to how many kilowatts?

A. 1,000 C. 100 B. 250 D. 10 277. REE Board Exam September 2000 What is 1 kW-hr in BTU? A. 4,186 C. 746 B. 3,413 D. 1,000 278. REE Board Exam October 1998

What is the work in ergs needed to raise a 10 g weight 100 m up?

A. 4.9 x 105 C. 98 x 10

7

B. 9.8 x 107 D. 1.96 x 10

7

279. REE Board Exam October 1999

The quantity of heat required to raise the temperature of water by 1C.

A. energy C. calorie B. specific heat D. BTU 280. REE Board Exam October 1999

When heat is transferred into any other form of energy or when other forms of energy are converted into heat, the total amount of energy is constant. This is known as

A. First law of thermodynamics B. Boyles law C. Specific heat D. Isothermal expansion 281. REE Board Exam September 2002 What is 10

12 ergs/sec in kW?

A. 100 kW C. 10 kW B. 1,000 kW D. 10,000 kW 282. REE Board Exam October 2000

An electric heater is used to heat up 600 grams of water. It takes 14 minutes to raise the temperature of water by 40C. If the supply voltage is 220 volts, what is the power rating of the heater neglecting heat losses?

A. 180 W C. 200 W B. 120 W D. 60 W 283. REE Board Exam April 2001

A 100 liter of water is heated from 20C to 40C. How many kWHR of electricity is needed assuming no heat loss?

A. 4.2 C. 5.6 B. 2.3 D. 3.7 284. REE Board Exam April 2002 Ten (10) kW is equal to ____ gram-cal/sec. A. 156 C. 2,388 B. 436 D. 425 285. ECE Board Exam November 1995

Two heaters A and B are in parallel across supply voltage V. Heater A produces 500 kcal in 20 minutes and B produces 1000 kcal in 10 minutes. The resistance of A is 10 ohms. What is the resistance of B, if the same heaters are connected in series voltage V?

A. 4.5 ohms C. 4.5 ohms B. 2.5 ohms D. 0.14 ohm 286. In the SI system of units, the unit of force is A. kg-wt C. Joule B. Newton D. N-m 287. The basic unit of electric charge is A. ampere-hour C. coulomb B. watt-hour D. farad 288. The SI unit of energy is A. Joule C. kcal B. kWh D. m-kg 289. The SI unit of energy is A. Joule C. kcal B. kWh D. m-kg 290. Two heating elements, each of 230-V, 3.5 kW rating

are first joined in parallel and then in series to heat same amount of water through the same range of temperature. The ratio of the time taken in the two cases would be

A. 1:2 C. 1:4 B. 2:1 D. 4:1 291. If a 220 V heater is used on 110 V supply, heat

produced by it will be ____ as much A. one-half C. one-fourth B. twice D. four times 292. For a given line voltage, four heating coils will

produce maximum heat when connected A. all in parallel B. all in series C. with two parallel pairs in series D. one pair in parallel with the other two in series 293. The electric energy required to raise the

temperature of a given amount of water is 1000 kWh. If heat losses are 25%, the total heating energy required is ____ kWh.

A. 1500 C. 1333 B. 1250 D. 1000 294. One kWh of energy equals nearly A. 1000 W C. 4186 J B. 860 kcal D. 735.5 W 295. A force of 10,000 N accelerates a body to velocity

0.1 km/s. The power developed is ____ kW. A. 1,000,000 C. 3600 B. 36,000 D. 1000 296. A 100 W light bulb burns on an average of 10 hours

a day for one week. The weekly consumption of energy will be ____ unit/s.

A. 7 C. 0.7 B. 70 D. 0.07 297. Two heaters, rated at 1000 W, 250 volts each, are

connected in series across a 250 volt, 50 Hz A.C.

mains. The total power drawn from the supply would be ____ watt.

A. 1000 C. 250 B. 500 D. 2000 298. One watt is equal to ____. A. 4.19 cal/sec C. 10

7 ergs/sec

B. 778 BTU/sec D. 10-7

ergs/sec 299. The current in an electric lamp is 5 amperes. What

quantity of electricity flows toward the filament in 6 minutes?

A. 30 C C. 72 C B. 3600 C D. 1800 C 300. An electric heater is rated at 120 volts, 1000 watts

and is used to boil water. Calculate the time in minutes to raise the temperature of 1 liter of water from 15C to boiling. The heater has an over-all efficiency of 92%.

A. 6.4 minutes C. 4.4 minutes B. 5.4 minutes D. 3.4 minutes 301. For a given line voltage, four heating coils will

produce maximum heat when connected A. all in parallel B. all in series C. with two parallel pairs in series D. one pair in parallel with the other two in series 302. Four heaters having the same voltage rating will

produce maximum heat if connected in A. Series C. Series-Parallel B. Parallel D. Parallel-Series 303. 1000 kW is equal to how many is ergs/sec. A. 2 x 10

13 C. 1 x 10

13

B. 1 x 1016

D. 2 x 1010

304. When current flows through heater coil, it glows but

supply wiring does not glow because A. supply wiring is covered with insulation wiring B. current through supply line flows at slower

speed C. supply wires are made of superior material D. resistance of heater coil is more than that of

supply wire

D. ELECTRIC CELLS 305. REE Board Exam October 1997

A load of 10 ohms was connected to a 12-volt battery. The current drawn was 1.18 amperes. What is the internal resistance of the battery?

A. 0.35 ohm C. 0.25 ohm B. 0.20 ohm D. 0.30 ohm 306. REE Board Exam April 1997

The electromotive force of a standard cell is measured with a potentiometer that gives a reading of 1.3562 V. When a 1.0 megaohm resistor is connected across the standard cell terminals, the potentiometer reading drops to 1.3560 V, what is the internal resistance of the standard cell?

A. 174.5 ohms C. 147.5 ohms B. 145.7 ohms D. 157.4 ohms 307. REE Board Exam April 1997

If a resistor rated at 5 watts and 6 volts are connected across a battery with an open circuit voltage of 6 volts. What is the internal resistance of the battery if the resulting current is 0.8 A?

A. 0.30 ohm C. 0.23 ohm B. 0.26 ohm D. 0.03 ohm 308. REE Board Exam October 1998

A 12 V battery of 0.05-ohm resistance and another battery of 12 V and 0.075 ohm resistance supply power to a 2-ohm resistor. What is the current through the load? A. 5.85 A C. 5.72 A

B. 5.63 A D. 5.91 A

309. REE Board Exam October 1996 The lead batteries A and B are connected in parallel. A has an open circuit voltage of 12 V and an internal resistance of 0.2 ohm. Battery B has an open circuit voltage of 12.2 V and an internal resistance of 0.3 ohm. The two batteries together deliver power to a 0.5 ohm power resistor. Neglecting effects of temperature, how much current is contributed by battery A?

A. 29.62 A C. 12.85 A B. 16.00 A D. 25.24 A 310. EE Board Exam October 1981

A charger, a battery and a load are connected in parallel. The voltage across the charger is 12.5 volts and the battery has an emf of 12 volts and internal resistance of 0.1 ohm. The load consists of a 2 ohms resistor. Find the current through the charger.

A. 6.61 A C. 6.42 A B. 6.25 A D. 6.50 A 311. REE Board Exam October 1996

A lead storage battery is rated at 12 volts. If the internal resistance is 0.01 ohm, what is the maximum power that can be delivered to the load?

A. 1,200 W C. 7,200 W B. 3,600 W D. 1,800 W 312. EE Board Exam April 1995

A 120-V battery having an internal resistance of 0.5 ohm is connected through a line resistance of 0.5 ohms to a variable load resistor. What maximum power will the battery deliver to the load resistor?

A. 36 watts C. 630 watts B. 63 watts D. 360 watts 313. REE Board Exam April 2002

A 12 volts battery has a 50 ampere-hour capacity. The internal resistance is 0.1 ohm. A 5 ohm load is connected for 5 hours. How many ampere-hours are still left?

A. 28.51 C. 38.23 B. 41.24 D. 35.92

314. REE Board Exam April 2002

Two-24 volt battery supply power to a 20 ohm load. One battery has 0.2 ohm internal resistance while the other has 0.4 ohm. What power does the load draws?

A. 28.4 W C. 30.8 W B. 22.2 W D. 18.6 W 315. ECE Board Exam March 1996 Which statement is not true? A. Secondary cell can be recharged B. The internal resistance of a cell limits the

amount of output current C. The negative terminal of a chemical cell has a

charge of excess electrons D. Two electrodes of the same metal provide the

highest voltage output 316. ECE Board Exam November 2001

In the operation of dry cell we normally refer to the supply of current load resistance where its current neutralizes the separated charges at the electrodes.

A. Aligning the cells B. Charging the cells C. Discharging the cells

D. Polarizing the cells 317. ECE Board Exam November 2000

Refers to a power source or cell which can be rechargeable

A. Battery C. Primary B. Secondary D. Storage 318. ECE Board Exam November 2001

In the operation of dry cell we normally refer to the supply of current load resistance where its current neutralizes the separated charge s at the electrodes.

A. Aligning the cells B. Charging the cells C. Discharging the cells D. Polarizing the cells 319. ECE Board Exam November 2000

The part of the cell of the solution that acts upon the electrodes providing a path for electron flow

A. Container C. Sealing way B. Electrolyte D. Electrolysis 320. ECE Board Exam April 1999

Type of cell used mostly for emergency equipment. It is light, small, and has a large capacity of power for its size.

A. Ni-Cd cell C. Silver-zinc cell B. Silver-cadmium cell D. Mercury cell 321. ECE Board Exam March 1996

The purpose of cells connected in parallel is to_____.

A. increase internal resistance B. increase in voltage output C. decrease current capacity

D. increase in current capacity 322. ECE Board Exam November 1995 Find the output of a four (4) lead acid cells. A. 3.2 V C. 5.8 V B. 8.4 V D. 1.6 V 323. ECE Board Exam November 1997

How many silver zinc cells in series are needed for a 9V battery?

A. 9 C. 3 B. 6 D. 7 324. ECE Board Exam November 1995

_____ is the specific gravity reading for a good lead acid cell.


Refers to a power source or cell that is not rechargeable?

A. Secondary C. Storage B. Primary D. Battery 326. ECE Board Exam April 1998 Which of the following is not a primary type cell? A. Zinc-chloride C. Silver oxide B. Silver-zinc D. Carbon zinc 327. ECE Board Exam November 1997

A battery should not be charged or discharged at a high current in order to avoid this defect.

A. Corrosion C. Buckling B. Sedimentation D. Sulphation 328. ECE Board Exam April 2001

It is a cell in which the chemical action finally destroys one of the electrons electrodes, usually the negative and cannot be recharged.

A. Dry cell C. Wet cell B. Secondary cell D. Primary cell

329. ECE Board Exam November 2001 Which of the following statements is not true? A. Output of solar cell is normally 0.5 V B. Edison cell is storage type C. The Ni-Cd cell is primary type D. Primary cells can be charged 330. ECE Board Exam April 2001

Which of the following statements is not true? A. A primary cell has irreversible chemical

reaction B. A carbon zinc cell has unlimited shelf life C. A storage cell has irreversible chemical

reaction D. A lead acid cell can be recharged 331. ECE Board Exam November 1999

A device that transforms chemical energy into electrical energy

A. Battery

B. Cell C. Primary battery D. Secondary battery

332. ECE Board Exam April 1999

What is the effect of connecting battery cells in parallel?

A. Current decreases B. Voltage increases C. Voltage decreases D. Current increases 333. ECE Board Exam November 1997

Determine how long a battery will last whose rating is 100 Ah, 24 volts and will run a 300 watts electronic equipment and a 50 watts light.

A. 6.85 hours C. 26.65 hours B. 50.05 hours D. 12.00 hours 334. ECE Board Exam April 2001

The process of reversing the current flow through the battery to store the battery to its original condition

A. Electrolysis C. Reverse flow B. Ionization D. Battery charge 335. ECE Board Exam November 2000

The type of cell commonly referred to as flashlight battery

A. Nickel-cadmium battery C. Dry cell B. Mercury cell D. Lead acid cell 336. ECE Board Exam November 1998

How does a battery behave whose cells are connected in series?

A. Increase current supply B. Reduces total voltage C. Increases voltage supply D. Reduces internal resistance 337. ECE Board Exam April 1998

Another very useful cell to solar cells however the junction is bombarded by beta particles from radioactive materials

A. Alkaline cells C. Selenium cells B. Nucleus cells D. Lithium cells 338. ECE Board Exam November 2001

The continuation of current flow within the cell there is no external load

A. Local action C. Self-discharge B. Polarization D. Electrolysis 339. ECE Board Exam November 1998

Type of power source in electronics that cannot be recharged after it has delivered its rated capacity

A. Cells B. Primary cells C. Battery D. Secondary cells

340. ECE Board Exam November 1995 Which has the largest diameter of the following dry cells?

A. Type C C. Type AAA B. Type AA D. Type D 341. ECE Board Exam April 1998

How many nickel-cadmium cells are needed in series for a 10 V battery?

A. 8 C. 5 B. 12 D. 10 342. ECE Board Exam March 1996

Current in a chemical cell refers to the movement of _____.

A. Negative ions only B. Negative and positive ions C. Positive ions only D. Negative hole charge 343. ECE Board Exam November 1998 Find the output of a two (2) lead acid cells. A. 0.952 V C. 3.2 V B. 2.1 V D. 4.2 V 344. ECE Board Exam November 2000

The liquid solution that forms ion charges in a lead acid battery

A. Electrolyte C. Sulfuric acid B. Hydrochloric acid D. Nitric acid 345. ECE Board Exam April 1998

Single device that converts chemical energy into electrical energy is called

A. Battery C. Solar B. Generator D. Cell 346. ECE Board Exam November 1995

There are _____ identical cells in parallel needed to double the current reading of each cells.

A. 3 C. 2 B. 4 D. 1 347. ECE Board Exam April 2001

What is the effect of connecting battery cells in series?

A. Voltage increases B. Current increases C. Voltage decreases D. Current decreases 348. ECE Board Exam November 2000

How long can a battery last with capacity of 50 ampere-hour running equipment of 5 amperes?

A. 250 hours C. 100 hours B. 25 hours D. 10 hours 349. ECE Board Exam April 1998

How long will a battery need to operate a 240-watt equipment, whose capacity is 100 Ah and 24 volts rating?

A. 10 hours C. 1 hour B. 5 hours D. 0.10 hour


What is affected when a lead battery is overcharged?

A. Carbon C. Plates B. Grid D. Electrolytes


When the cells are in series voltages add, while current capacity is _____.

A. The same as one cell B. Zero C. Infinite D. The sum of each cell 352. ECE Board Exam April 1999

Refers to an action in the operation of secondary cells reforming the electrodes in a chemical reaction where dc voltage is supplied externally.

A. Polarizing cells B. Charging cells C. Aligning cells D. Discharging cells 353. ECE Board Exam November 1999

What type of cell that cannot be recharged which cannot restore chemical reaction?

A. Primary cell B. Secondary cell C. Lead-acid wet cell D. Nickel-cadmium cell 354. ECE Board Exam November 2000

An ordinary flashlight battery is which of the following?

A. A load C. A storage cell B. A dry cell D. A wet cell 355. ECE Board Exam April 1998 Refers to dry storage cell carbon zinc. A. cell B. Edison cell C. Mercury cell D. Nickel cadmium cell 356. ECE Board Exam April 1998

What is the other term of the secondary cells considering its capability to accept recharging?

A. Reaction cell C. Storage cell B. Primary cell D. Dry cell


Find the required battery capacity needed to operate an equipment of 30 amperes at 5 hours.

A. 6 C. 3 B. 30 D. 150 358. ECE Board Exam March 1996

When batteries have cells connected in series the effect is

A. Reduced output voltage B. Increased current supply C. Increased voltage supply

D. Reduced internal resistance 359. ECE Board Exam November 2000

Find the required battery capacity needed to operate on electronic equipment with power rating of 200 watts and 10 volts at 6 hours.


A cell(s) that can be operated or used in a horizontal, vertical or any position where its electrolyte cannot be spilled in any position

A. Primary cells C. Dry cells B. Secondary cells D. Battery

361. ECE Board Exam April 1999

It is an indication of the current supplying capability of the battery for a specific period of time, e.g. 400 ampere-hour.

A. Rating C. Capability B. Capacity D. Current load 362. ECE Board Exam March 1996 Which of the following is not a secondary type cell? A. Lithium C. Silver cadmium B. Lead-acid D. Silver-zinc 363. ECE Board Exam March 1996

How many lithium cells in series are needed for a 12 V battery?

A. 12 cells C. 8 cells B. 4 cells D. 10 cells 364. ECE Board Exam November 1996

Component of solar battery which uses light energy to produce electromagnetic force

A. Alkaline cell C. Lithium cell B. Polymer cell D. Selenium cell 365. ECE Board Exam March 1996

If a dry cell has an internal resistance of 0.50 ohm and emf of 2 volts, find power delivered in a one ohm resistor.

A. 1.33 watts C. 3.66 watts B. 1.66 watts D. 1.77 watts 366. ECE Board Exam March 1996

Parallel cells have the same voltage as one cell but have _____.

A. Unstable resistance B. Less current capability C. Fluctuating power output D. More current capacity 367. ECE Board Exam April 1999

A battery with capacity of 100 Ah and 12 volts rating will run an electronic equipment at exactly 20 hours, how much power is needed?

A. 60 watts C. 10 watts B. 20 watts D. 30 watts 368. ECE Board Exam March 1996

It is the output voltage of a carbon-zinc cell. A. 3.5 V C. 1.5 V B. 2.5 V D. 0.5 V 369. ECE Board Exam March 1996

What is the reason why more cells can be stored in a given area with dynamic cells?

A. They consume less power B. They are smaller C. They are larger D. They travel faster 370. ECE Board Exam November 1997

A radio equipment will be used at 70% at 50 amperes rating for 5 hours. How much capacity of dry battery is needed?

A. 35 C. 250 B. 17.5 D. 175 371. The potential at the terminals of the battery falls

from 9 V on open circuit to 6 volts when a resistor of 10 ohms is connected across its terminals. What is the internal resistance of the battery?

A. 5 C. 3 B. 4 D. 2 372. A battery is formed of five cells joined in series.

When the external resistance is 4 ohms, the current is 1.5 A and when the external resistance is 9 ohms, the current falls to 0.75 A. Find the internal resistance of each cell.

A. 0.5 ohm C. 0.2 ohm B. 1.0 ohm D. 0.3 ohm

373. A 12 V source with 0.05 resistance is connected in series with another 12 volt with 0.075

resistance with a load of 2 . Calculate the power dissipated in the load.

A. 365 watts C. 105 watts B. 127 watts D. 255 watts

374. A 24 V source with 0.05 resistance is connected

in parallel with another 24 V with 0.075 resistance

to a load of 2 . Calculate the current delivered by

the source with a 0.05 resistor. A. 7 amperes C. 5 amperes B. 10 amperes D. 12 amperes 375. A battery can deliver 10 joules of energy to move 5

coulombs of charge. What is the potential difference between the terminals of the battery?

A. 2 V C. 0.5 V B. 50 V D. 5 V 376. An ordinary dry cell can deliver about ____

continuously. A. 3 A B. 2 A C. 1/8 A D. none of the above 377. Cells are connected in series when ____ is

required.

A. high voltage B. high current C. high voltage as well as high current D. none of the above 378. Cells are connected in seriesparallel when ____ is

required. A. high current B. high voltage C. high current as well a high voltage D. none of the above 379. Four cells, each of internal resistance 1 ohm, are

connected in parallel. The battery resistance will be ____

A. 4 ohms C. 2 ohms B. 0.25 ohm D. 1 ohm 380. The e.m.f. of a cell depends upon ____ A. nature of electrodes and electrolyte B. size of electrodes C. spacing between electrodes D. none of the above 381. In order to get maximum current in series parallel

grouping, the external resistance should be ____ the total internal resistance of the battery.

A. less than B. more than C. equal to D. none of the above 382. The positive terminal of a 6-V battery is connected

to the negative terminal of a 12-V battery whose positive terminal is grounded. The potential at the negative terminal of the 6V battery is ____ volt.

A. +18 C. -6 B. 12 D. -18 383. The positive terminal of a 6-V battery is connected

to the negative terminal of a 12-V battery whose positive terminal is grounded. The potential at the positive terminal of the 6-V battery is ____ volt.

A. +6 C. -12 B. -6 D. +12 384. Active materials of a lead-acid cell are A. lead peroxide B. sponge lead C. dilute sulfuric acid D. all of the above 385. During the charging of lead-acid cell A. its cathode becomes dark chocolate brown in

colour B. its voltage increases C. it gives out energy D. specific gravity of H2SO4 is decreased 386. The ratio of Ah efficiency to Wh efficiency of a lead-

acid cell is A. always less than one B. just one

C. always greater than one D. either A or B 387. The capacity of a cell is measured in A. watt-hours C. amperes B. watts D. ampere-hours 388. The capacity of a lead-acid cell does NOT depend

on its A. rate of charge B. rate of discharge C. temperature D. quantity of active materials 389. As compared to constant-current system, the

constant-voltage system of charging a lead-acid cell has the advantage of

A. avoiding excessive gassing B. reducing time of charging C. increasing cell capacity D. both B and C 390. Sulphation in a lead-acid battery occurs due to A. trickle charging B. incomplete charging C. heavy discharging D. fast charging 391. The active materials of a nickel-iron battery are A. nickel hydroxide B. powdered iron and its oxides C. 21% solution of caustic potash D. all of the above 392. During charging and discharging of a nickel-iron cell A. its e.m.f. remains constant B. water is neither formed nor absorbed C. corrosive fumes are produced D. nickel hydroxide remains unsplit 393. As compared to a lead-acid cell, the efficiency of a

nickel-iron cell is less due to its A. lower e.m.f. B. smaller quantity of electrolyte used C. higher internal resistance D. compactness 394. Trickle charging of a storage battery helps to A. prevent sulphation B. keep it fresh and fully charged C. maintain proper electrolyte level D. increase its reserve capacity 395. A dead storage battery can be revived by A. a dose of H2SO4 B. adding so-called battery restorer C. adding distilled water D. none of the above 396. The sediment which accumulates at the bottom of a

lead-acid battery consist largely of A. lead-peroxide B. lead-sulphate

C. antimony-lead alloy D. graphite 397. The reduction of battery capacity at high rates of

discharge is primarily due to A. increase in its internal resistance B. decrease in its terminal voltage C. rapid formation of PbSO4 on the plates D. non-diffusion of acid to the inside active

materials 398. Floating battery system are widely used for A. power stations B. emergency lighting C. telephone exchange installation D. all of the above 399. Any charge given to the battery when taken off the

vehicle is called A. bench charge C. float charge B. step charge D. trickle charge 400. Storage battery electrolyte is formed by the

dissolving of ____ acid in water. A. hydrochloric C. acetic B. sulfuric D. atric 401. The central terminal of a dry cell is said to be A. positive C. neutral B. negative D. charged 402. A 24 V battery of internal resistance r = 4 is

connected to a variable resistance R, the rate of heat dissipation in the resistor is maximum when the current drawn from the battery is I. Current drawn from the battery will be I/2 when R is equal to

A. 8 C. 16 B. 12 D. 20 403. What is the other term used for rechargeable

battery? A. primary B. lead-acid C. storage D. nickel-cadmium E. NETWORK THEOREMS 404. REE Board Exam April 1997

A circuit consisting of three resistors rated: 10 ohms, 15 ohms and 20 ohms are connected in delta. What would be the resistance of the equivalent wye connected load? A. 0.30, 0.23 & 0.15 ohm B. 3.0, 4.0 & 5.0 ohms C. 3.33, 4.44 & 6.66 ohms D. 5.77, 8.66 & 11.55 ohms


The equivalent wye element of a 3 equal resistors each equal to R and connected in delta is

A. R C. R/3 B. 3R/2 D. 3R

406. EE Board Exam April 1988 A Barangay power station supplies 60 kW to a load over 2,500 ft, 100 mm

2, two-conductor copper

feeder, the resistance of which is 0.078 ohm per 1000 ft. The bus bar voltage is maintained constant at 600 V. Determine the load current.

A. 105 A C. 110 A B. 108 A D. 102 A 407. EE Board Exam October 1986

An LRT car, 5 km distance from the Tayuman station, takes 100 A over a 100 mm hard drawn copper trolley wire having a resistance of 0.270 ohm per km. The rail and ground return has a resistance of 0.06 ohm per km. If the station voltage is 750 V, what is the voltage of the car?

A. 585 V C. 595 V B. 590 V D. 580 V 408. EE Board Exam April 1989

The LRT trolley system 10 miles long is fed by two substations that generate 600 volts and 560 volts, respectively. The resistance of the trolley wire and rail return is 0.3 ohm per mile. If the car is located 4 miles from the 600 volt station draws 200 A from the line. How much is the current supplied by each station? A. 133.33 A, 66.67 A B. 123.67 A, 76.33 A C. 117.44 A, 82.56 A D. 125.54 A, 63.05 A

409. EE Board Exam April 1992

In Manila, the LRT runs between Gil Puyat Station and Tayuman Station, which is 4 km apart and maintains voltages of 420 volts and 410 volts respectively. The resistance of go and return is 0.05 ohm per km. The train draws a constant current of 300 A while in motion. What are the currents supplied by the two stations if the train is at the distance of minimum potential?

A. 175 A, 125 A C. 164 A, 136 A B. 183 A, 117 A D. 172 A, 123 A 410. EE Board Exam October 1986

An LRT car, 5 km distance from the Tayuman station, takes 100 A over a 100 mm hard drawn copper trolley wire having a resistance of 0.270 ohm per km. The rail and ground return has a resistance of 0.06 ohm per km. If the station voltage is 750 V, what is the efficiency of transmission?

A. 78% C. 74% B. 81% D. 79%


A barangay power station supplies 60 kW to a load over 2,500 ft of 0002-conductor copper feeder the resistance of which is 0.078 ohm per 1,000 ft. The bus bar voltage is maintained constant at 600 volts. Determine the maximum power which can be transmitted.

A. 220.35 kW C. 242.73 kW B. 230.77 kW D. 223.94 kW


Twelve similar wires each of resistance 2 ohms are connected so as to form a cube. Find the resistance between the two diagonally opposite corners.

A. 1.45 ohms C. 2.01 ohms B. 1.66 ohms D. 1.28 ohms 413. EE Board Exam April 1991

Twelve similar wires each of resistance 2 ohms are connected so as to form a cube. Find the resistance between the two corners of the same edge.

A. 1.133 ohms C. 1.125 ohms B. 1.102 ohms D. 1.167 ohms


Twelve identical wires each of resistance 6 ohms are arranged to form the edge of a cube. A current of 40 mA is led into the cube at one corner and out at the other diagonally opposite corners. Calculate the potential difference developed between these corners.

A. 0.20 V C. 0.22 V B. 0.28 V D. 0.24 V

415. EE Board Exam August 1976 Find the value of the voltage V.

G

V

1

4

0.1

+

-

24 V 12 V

Lamp

60 W

12 V

A. 12.34 V C. 12.19 V B. 11.24 V D. 11.66 V 416. EE Board Exam April 1982

Referring to the circuit diagram below, if the charger voltage is 130 volts and the battery voltage is 120 volts, solve for the current Ib.

3

40

2

+

-

Battery

ChargerBattery

Ib

A. -0.215 A C. -0.306 A B. 0.215 A D. 0.306 A 417. EE Board Exam August 1977

In the figure below R1 = 1 ohm, R2 = 1 ohm, R3 = 3 ohms, I2 = 2 A and VB = 120 V. Find Eg.

G

R1

R3

I2

+

-

Eg VB

R2

A. 182.41 V C. 164.67 V B. 153.32 V D. 157.22 V 418. EE Board Exam October 1980, April 1984

In the dc circuit as shown, the high resistance voltmeter gives a reading of 0.435 volt. What is the value of the resistance R?

V

+

-

+ -

10

50

R

20

12 V

A. 4 ohms C. 3 ohms

B. 5 ohms D. 2 ohms 419.

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Question Bank in DC Circuits