Electricity Practice

8/12/2019 Electricity Practice

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Electric fields

1. A positively charged sphere falls vertically in a vacuum between two long parallel plates

carrying opposite charges. Which oneof the following diagrams best shows the path followed

by the sphere?

+

+

+

+

+

+

+

+

+

+

+

+

A . B .

C . D .

(1)

2. Which one of the following is a correct definition of electric potential difference between two

points?

A. he power to move a small positive charge between the two points.

B. he wor! done to move a small positive charge between the two points.

C. he power per unit charge to move a small positive charge between the two points.

D. he wor! done per unit charge to move a small positive charge between the two points.(1)

3. he diagram below shows two long parallel plates that are oppositely charged. A positive test

charge +qis placed along the dotted line "#.

"+ q

#

he charge +qis moved from " to #. Which oneof the following best shows the variation with

distance dfrom " of the magnitudeFof the force on +q?

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A . F

'

B . F

'" # d " # d

C . F

'

D . F

'" # d " # d

(1)

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4. he diagram below illustrates some e(uipotential lines between two charged parallel

metal plates.

' . ) m

+

+ + +

* '

, '

- '

'

he electric field strength between the plates is

A. , / C)

.

B. * / C)

.

C. ,'' / C)

.

D. *'' / C)

.(1)

5. Electric field strengthis defined as

A. the force e%erted on a test charge.

B. the force per unit positive charge.

C. the force per unit charge.

D. the force per unit charge e%erted on a positive test charge.(1)

6. A charged particle 0 is accelerated between two charged metal plates " and # separated by a

distance d. he particle starts from rest at plate ".

.

p l a t e " p l a t e #

0

d

he !inetic energy of 01 when it reaches plate #1 isK. he magnitude of the charge on 0 is e.

he magnitude of the electric field strength between the plates is

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A..

K

de

B..

Ke

d

C..

ed

K

D..

d

Ke

(1)

7. he electric field strength at a point may be defined as

A. the force e%erted on unit positive charge placed at that point.

B. the force per unit positive charge on a small test charge placed at that point.

C. the wor! done on unit positive charge to move the charge to that point from infinity.

D. the wor! done per unit positive charge to move a small test charge to that point from

infinity.(1)

8. wo point charges of magnitude +Qand 2Qare fi%ed at the positions shown below. At which

point is the electric field due to the two charges most li!ely to be 3ero?

+ Q Q

A . B . C . D .

(1)

9. his (uestion is about the physics of a lightning stri!e.

4n a simple model of a thundercloud1 a negative charge is built up on the base of the cloud by

the process of charge separation. he resulting electric fieldbetween the cloud and the ground

is appro%imately the same as that between two infinite parallel charged plates. When the charge

on the base of the cloud reaches a certain value1 a lightning stri!e occurs between the ground

and the base of the cloud.

t h u n d e r c l o u d

5 ' ' m

g r o u n d

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6a7 8%plain what is meant by the term charge separation.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

6b7 Define electric field strength.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

6c7 9n the above diagram1 draw the electric field pattern between the ground and the base of

the cloud.(3)

he electric field strengthEbetween two infinite1 parallel charged plates is given by

E: '

where is the charge on an area of ) mof one plate.

;ust before a lightning stri!e1 a particular thundercloud carries a charge of ' C spread over its

base. he area of the base of the cloud is < = )',m

.

6d7 6i7 >how that the magnitude of the electric field between the base of the cloud and the

ground is appro%imately = )'5m

).

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...........................................................................................................................

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...........................................................................................................................

...........................................................................................................................(3)

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6ii7 >tate twoassumptions made when applying this formula.

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6e7 he base of the cloud is at an average height of 5'' m. Calculate the potential difference

between the ground and the cloud base @ust before the lightning stri!e.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

When a lightning stri!e occurs between the ground and the base of this thundercloud1 the cloud

completely discharges in a time of ' ms.

6f7 6i7 Calculate the average current in the lightning stri!e.

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...........................................................................................................................(1)

6ii7 8stimate the energy released during the lightning stri!e.

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...........................................................................................................................(3)

(Total 18 marks)

10. Which one of the field patterns below could be produced by two point charges?

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A .

C .

B .

D .

(1)

11. he diagram below shows two parallel conducting plates that are oppositely charged.

+++ + +

"

#

he line "# is perpendicular to the plates.

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Which of the following diagrams shows the variation along the line "# of the magnitudeEof

the electric field strength between the plates?

8

8

8

8

"

"

"

"

#

#

#

#

d i s t a n c e

d i s t a n c e

d i s t a n c e

d i s t a n c e

A . B .

C . D .

(1)

12. Which diagram below best represents the electric field pattern between a positively charged

conducting sphere and an earthed metal plate?

A . B .

C . D .

(1)

13. A proton and an alpha particle are accelerated from rest from the positively charged plate " to

the negatively charged plate #.

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+

+ + + + +

p r o t o n a l p h a p a r t i c l e

m i d p o i n t

#

"

At the midpoint between the plates1 the proton has a !inetic energyE. At this point1 the alpha

particle has a !inetic energy

A.

E

.

B. E.

C. E.

D. -E.

(1)

14. he diagram below shows two lines of e(uipotential in a region of a uniform electric field. ine

" has a potential of +5' and line # has a potential of +)''. he distance between " and # is

.' cm.

+ 5 ' + ) ' '

" #

. ' c m

Whichone of the following correctly gives the direction of the electric field and its strength?

irection !tren"t# $ % cm&1

A. " # 5

B. " # )''

C. # " 5

D. # " )''

(1)

15. he electric field strength at a point may be defined as

A. the force e%erted on unit positive charge placed at that point.

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B. the force per unit positive charge on a small test charge placed at that point.

C. the wor! done on unit positive charge to move the charge to that point from infinity.

D. the wor! done per unit positive charge to move a small test charge to that point from

infinity.(1)

16. 4n the circuit below1 which meter is notcorrectly connected?

A

A

)

?

-

A. )

B.

C.

D. -(1)

17. he graph below shows the currentvoltage characteristics of a filament lamp.

-

) ,

*

'' - , * ) '

o l t a g e V

C u r r e n t = ) ' A ?

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he resistance of the filament at -.' is

A. 5' E.

B. - ''' E.

C. * ''' E.

D. ,- ''' E.(1)

18. 4n the circuit below1 ncharge carriers pass the point 0 in a time t. 8ach charge carrier has charge

q.

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0

he current in the circuit is given by the e%pression

A. t

q

.

B. tnq

.

C. n

qt

.

D. nqt.(1)

19. 4n the circuit shown1 the voltmeter has a resistance of ' !E and the battery has an emf of ,.'

and negligible internal resistance.

, . '

) ' ! ' !

' !

he reading on the voltmeter is

A. .' .

B. .' .

C. -.' .

D. ,.' .(1)

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20. 4n the circuits below1 the cells each have the same emf and 3ero internal resistance. All the

resistors have the same resistance.

C i r c u i t " C i r c u i t # C i r c u i t F

Which of the following gives the current through the cells in order of increasing magnitude?

owest current Gighest current

A. " # F

B. F " #

C. # F "

D. # " F

(1)

21. he graph shows the variation with applied potential difference Vof the currentI in an electrical

component.

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I

I

''

0

V v

)

)

Whichone of the following gives the resistance of the component at point 0?

A. he gradient of the line at 0

B. he reciprocal of the gradient of the line at 0

C. he ratio )

)

V

I

D. he ratio )

)

I

V

(1)

22. he diagrams below show combinations "1 # and F of three resistors1 each resistor having the

same resistance.

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c o m b i n a t i o n " c o m b i n a t i o n Fc o m b i n a t i o n #

Whichone of the following shows the resistances of the combinations in increasing order of

magnitude?

lowest

#i"#est

A. # " F

B. F " #

C. " # F

D. F # "

(1)

23. he current in the circuit shown below is constant when the switch is closed.

H

r

he energy transfer in the internal resistance r of the battery is )5 ; when a charge of -' Cpasses through it. Ior the same amount of charge1 -5 ; of energy is transferred in the resistor H.

Which of the following gives the emf of the battery?

A.+

-'

)5

B.

+

-'

?'

C.+

-'

-5

D.+

-'

,'

(1)

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24. A battery of emfEand negligible internal resistance is connected to three resistors1 each

of resistanceR1 a voltmeter and a switch1 as shown below.

E

R R

R

he voltmeter has infinite resistance.

What are the readings on the voltmeter when the switch is open and when it is closed?

!witc# o'en !witc# closed

A. ' less than JE

B. ' JE

C. JE less than JE

D. JE JE

(1)

25. A battery is connected in series with a resistorR. he battery transfers ''' C of charge

completely round the circuit. During this process1 5'' ; of energy is dissipated in the resistor

Rand ) 5'' ; is e%pended in the battery.

he emf of the battery is

A. .'' .

B. ).5 .

C. '.


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A

A

A

A

A .

C .

B .

D .

(1)

27. he variation with potential difference V of the currentIin an electric lamp is shown below.

I

I p

p'

' V V

0

At point 01 the current isIp1 the potential difference is Vpand the gradient of the tangent to the

curve is G. What is the resistance of the lamp at point 0?

A. G

)

B. G

C. p

p

V

I

D. p

p

I

V

(1)

28. he drift velocity of the electrons in a copper wire in which there is an electric current is

A. e(ual to the speed of light.

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B. close to that of the speed of light.

C. of the order of a few !ilometres per second.

D. of the order of a few millimetres per second.(1)

29. A heater has a resistanceR when the potential difference across it is ). 4n the circuit below1 itis connected in series with a , supply and a resistor >.

? ,

>

o ensure that the potential difference across the heater is ) 1 the resistance of the resistor >

should be

A.

R

.

B. ?

R

.

C.

?R

.

D. R.(1)

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30. 4n the two circuits " and # below1 each cell has an emfEand negligible internal

resistance. 8ach resistor has a resistanceR.

c i r c u i t " c i r c u i t #

E E

RR

R

he power dissipated in circuit " isP.

he best estimate for the power dissipated in circuit # is

A..

-

P

B..

P

C. P.

D. -P.(1)

31. he graph below shows the variation with voltageVof the currentI in three resistors "1#

and F.

I

0V'

"

#

F

Which of the following corresponds to resistors for which the resistance increases with

increasing current?

A. " only

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B. F only

C. " and F

D. # and F(1)

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32. A battery is connected to a resistor as shown below.

e n e r g y t r a n s f e r r e d E B

e n e r g y t r a n s f e r r e d E H

he battery transfers energyEBwhen charge Qpasses completely around the circuit and the

resistor transfers energyEH. he emf of the battery is e(ual to

A.

.K

HE

B.

.KBE

C.

.K

HB EE +

D.

.K

HB EE

(1)

33. 4n the circuit shown below1 the cell has negligible internal resistance.

I ?

R

I )

R

I

Which of the following e(uations is correct?

A. I): I

B. I): I

C. I: I

D. I: I)(1)

34. he graph below shows the variation with potential difference Vof the currentIin an electrical

component.

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I

' ' V ' V

Which oneof the following is a correct statement about the resistance of the component?

A. Ior potential differences greater than V'1 the resistance is constant.

B. Ior potential differences greater than V'1 the resistance decreases with increasing

potential difference.

C. he variation of current with potential difference is linear and so 9hmLs law is obeyed.

D. Ior potential differences less than V'1 the resistance is 3ero.

(1)

35. he resistors in each of the circuits shown below each have the same resistance.

c i r c u i t 0 c i r c u i t K c i r c u i t >

Which of the following gives the circuits in order of increasin"total resistance?

A. 0 K >

B. K 0 >

C. > K 0

D. 0 > K(1)

36. A cell of emfE and internal resistance r is connected to a variable resistor. A voltmeter is

connected so as to measure the potential difference across the terminals of the cell. Which one

of the following is the correct circuit diagram of the arrangement?

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A .

C .

B .

D .

E

E

E

E

r

r

r

r

(1)

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37. 4n which oneof the circuits is it possible to vary the current in the lamp by ad@usting the

variable resistor? he cell has negligible internal resistance.

A . B .

C . D .

(1)

38. 4n the circuit below1 the battery has negligible internal resistance. amps 1 M and / which

have different resistance are connected as shown.

M

/

Which oneof the following is always true?

A. amps and / have the same current through them.

B. amps and M have the same current through them.

C. amps and / have the same potential difference across them.

D. amps and M have the same potential difference across them.(1)

39. he element of an electric heater has a resistance R when in operation. What is the resistance of

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a second heater that has a power output three times as large at the same operating voltage?

A. N

R

B. ?

R

C. R

D. NR(1)

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40. 4n the circuit below the battery has emf ,.' and negligible internal resistance. he

three resistors each have resistance )' . A high resistance voltmeter is connected as shown.

, . '

) ' ) '

) '

he reading of the voltmeter is

A. .' .

B. .' .

C. -.' .

D. ,.' .(1)

41. A conductor of constant resistance dissipates ,.' W of power when the potential difference

across it is ) . he power that will be dissipated in this conductor when the potential

difference across it is - is

A. ,.' W.

B. ) W.

C. - W.

D. -* W.(1)

42. Which of the following is a correct statement of 9hmLs law?

A. he resistance of a conductor is always constant.

B. he current in a conductor is always proportional to the potential difference across the

conductor.

C. he resistance of a conductor increases with increasing temperature.

D. he resistance of a conductor is constant only if the temperature of the conductor is

constant.(1)

43. A resistor of resistance ).' is connected in series with a battery. he current in the circuit is

.' A.

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he resistor is now replaced by a resistor of resistance of -.' . he current in this circuit is ).'

A.

. ' A

) . '

1 . 0A

- . '

he best estimate for the internal resistance of the battery is

A. ).' .

B. .' .

C. -.' .

D. 5.' .

(1)

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44. wo filament lamps " and # are designed to operate at normal brightness when the

potential difference across the lamps is , . 8ach lamp will @ust light when the potential difference

across it is .

he two lamps are connected in parallel to a - supply of negligible internal resistance as

shown below.

-

"

#

he filament of lamp " brea!s so that there is no current in it. he filament of lamp # will

A. glow at normal brightness.

B. glow at more than normal brightness.

C. glow more dimly.

D. stay at the same brightness.(1)

45. 4n the circuit below1 resistors "1 # and F are connected in series with a N.' supply.

'

" # F

+ N . '

? ' ' ' ? ' ' '

V

Hesistors " and F are fi%ed resistors of resistance ''' . he resistance of resistor # may be

varied between 3ero and ''' .

Which of the following gives the ma%imum range of potential difference Vacross the resistors" and #?

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A. ' to ,.'

B. .' to ,.'

C. -.5 to ,.'

D. -.5 to N.'

(1)

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46. A metal conductor is negatively charged. 4t is connected to earth using a metal wire1 as

illustrated below.

w i r e

e a r t h

n e g a t i v e l y c h a r g e dc o n d u c t o r

What is the movement of charge as the conductor is earthed?

A. 0ositive charge moves from earth to the conductor.

B. /egative charge moves to earth from the conductor.

C. /egative charge moves from the conductor and positive charge moves from earth.

D. 0ositive charge from the wire moves to the conductor and negative charge moves to earth.(1)

47. Which of the following is a unit for electrical resistance?

A. WA

B. A)

C. W

s

D. W

(1)

48. he wor! done on a positive point charge of magnitude .' nC as it is moved at constant speed

from one point to another is ) n;. he potential difference between the two points is

A. '.' .

B. '.5 .

C. -.' .

D. , .(1)

49. he graph below shows the variation with currentIof the potential difference Vacross a

filament lamp.

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) .

) . '

' . *

' . ,

' . -

' .

' . ' . ') . 5) . '' . 5' . '

V v o l t s

I m A

he resistance of the lamp whenI: ).5 mA is

A. N5' .

B. -'' .

C. '.N5 .

D. '.-' .

(1)

50. 4n which oneof the circuits below is it possible to vary the current in the lamp by ad@usting the

variable resistor? he cell has negligible internal resistance.

A . B .

C . D .

(1)

51. A voltmeter of resistance 5' !is connected in a circuit as shown in the diagram below.

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e . m . f . : )

R

V

) ' !

5 ' !

he emf of the battery is ) and the resistance of the resistor is )' !. he internal resistance

of the battery is negligible.

he reading of the voltmeter is

A. '.' .

B. .' .

C. )' .

D. ) .(1)

52. he graph shows the currentvoltage 6IV7 characteristic of an electrical component.

I

I

'

)

V ' V ) V'

What is the resistance of the component at a potential difference V)and how does the resistance

change1 if at all1 between potential differences V'and V).

resistance at V1 c#an"e etween

V0and V1

A.)

') 76

I

VV no change

B.

') 76

I

VV decreases

C.)

)

I

Vno change

D.)

)

I

V

decreases

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(1)

53. he circuit contains a battery of e.m.f. ) and negligible resistance.

)

5 E

) 5 E

What is the potential difference across the 5 E resistor?

A. .'

B. -.5

C. 5.'

D.


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55. hree networ!s "1 # and F are shown below. 8ach resistor has the same resistance.

" # F

Which list shows the networ! resistances in increasing order of magnitude?

least P greatest

A. " # F

B. # " F

C. # F "

D. F " #(1)

56. Which graph best represents the relationship between the currentIand the voltage Vof a

filament lamp.

A . V

'

B . V

'' I ' I

C . V

'

D . V

'' I ' I

(1)

57. 4n the circuit below1 the battery has negligible internal resistance. hree identical lamps 1 M

and / of constant resistance are connected as shown.

he filament of lamp / brea!s. Which of the following shows the subse(uent changes to the

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brightness of lamp and lamp M?

am' am' *

A. stays the same decreases

B. increases stays the same

C. increases decreases

D. decreases increases

(1)

58. 4n the circuit below1 the voltmeter has a resistance )'' !. he battery has negligible internal

resistance and emf , .

he reading on the voltmeter is

A. ' .

B. .

C. .

D. - .(1)

59. 4n the circuit shown below1 the cell has negligible internal resistance.

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Which of the following e(uations is correct?

A. I): I

B. I): I

C. I: I

D. I: I)(1)

60. hree identical resistors of constant resistance are connected in series to a battery of negligible

internal resistance. he total power dissipated in the circuit is P.

he three resistors are now connected in parallel. he total power dissipated is

A..

?

P

B. P.

C. P.

D. NP.(1)

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61. his (uestion is about a filament lamp.

6a7 9n the a%es below1 draw a s!etchgraph to show the variation with potential difference V

of the currentIin a typical filament lamp 6theIVcharacteristic7. !Note:this is a s"etch-

graph# $o% do not need to add an$ val%es to the a&es'.

V

I''

(1)

6b7 6i7 8%plain how the resistance of the filament is determined from the graph.

...........................................................................................................................

...........................................................................................................................(1)

6ii7 8%plain whether the graph you have s!etched indicates ohmic behaviour ornon

ohmic behaviour.

...........................................................................................................................

...........................................................................................................................(1)

A filament lamp operates at ma%imum brightness when connected to a ,.' supply. At

ma%imum brightness1 the current in the filament is )' mA.

6c7 6i7 Calculate the resistance of the filament when it is operating at ma%imum

brightness.

...........................................................................................................................

(1)

6ii7 #ou have available a - supply and a collection of resistors of a suitable power

rating and with different values of resistance. Calculate the resistance of the

resistor that is re(uired to be connected in series with the supply such that the

voltage across the filament lamp will be ,.' .

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

(2)(Total 6 marks)

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62. his (uestion is about electrical energy and associated phenomena.

+,rrent electricit-

A cell of electromotive force 6emf7Eand internal resistance ris connected in series with a

resistor H1 as shown below.

H

rE

he cell supplies *.) = )'; of energy when 5.* = )'C of charge moves completely round the

circuit. he current in the circuit is constant.

6i7 Calculate the emfEof the cell.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

6ii7 he resistor H has resistance ,.' E. he potential difference between its terminals is). . Determine the internal resistance r of the cell.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(3)

6iii7 Calculate the total energy transfer in the resistor H.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

6iv7 Describe1 in terms of a simple model of electrical conduction1 the mechanism by which

the energy transfer in the resistor H ta!es place.

.....................................................................................................................................

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.....................................................................................................................................(5)

(Total 12 marks)

63. his (uestion is about electric circuits.

>usan sets up the circuit below in order to measure the currentvoltage 6I-V7 characteristic of a

small filament lamp.

A

? . '

>

he supply is a battery that has an emf of .' and the ammeter and voltmeter are considered

to be ideal. he lamp is labelled by the manufacturer as Q olts1 '., WattsR.

6a7 6i7 8%plain what information this labelling provides about the normal operation of the

lamp.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

6ii7 Calculate the current in the filament of the lamp when it is operating at normal

brightness.

...........................................................................................................................

...........................................................................................................................

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...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

>usan sets the variable resistor to its ma%imum value of resistance. >he then closes the switch >and records the following readings.

Ammeter reading : '.)* A oltmeter reading : '.,'

>he then sets the variable resistor to its 3ero value of resistance and records the following

readings.

Ammeter reading : '.' A oltmeter reading : .,

6b7 6i7 8%plain why1 by changing the value of the resistance of the variable resistance1 the

potential difference across the lamp cannot be reduced to 3ero or be increased to.' .

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

6ii7 Determine the internal resistance of the battery.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(3)

6c7 Calculate the resistance of the filament when the reading on the voltmeter is

6i7 '.,' .

...........................................................................................................................

...........................................................................................................................(1)

6ii7 ., .

...........................................................................................................................

...........................................................................................................................(1)

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6d7 8%plain why there is a difference between your answers to 6c76i7 and 6c76ii7.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

(2)

6e7 Ssing the a%es below1 draw a s!etchgraph of the 4 characteristic of the filament

of the lamp. !Note( this is a s"etch-graph# $o% do not need to add an$ val%es to the

a&es.'

I

V'

'(1)

he diagram below shows an alternative circuit for varying the potential difference across the

lamp.

? . '

"

#

F

he potential divider "F has a potential of .' across it. When the contact is at the position #1

the resistance of "# e(uals the resistance of #F which e(uals ) E. he resistance of the lamp

is - E.

6f7 Calculate the potential difference across the lamp.

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.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(4)

(Total 18 marks)

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45/108

) . ,

) . 5

) . -

) . ?

) .

) . )

) . '

' . N '

' . * '

' . < '

' . , '

' . 5 '

' . - '

' . ? '

' . '

' . ) '

' . '

V

' . ' ' . ) ' ' . ' ' . ? ' ' . - ' ' . 5 ' ' . , ' ' . < ' ' . * ' ' . N ' ) . ' ) . ) ) . ) . ?

I A

6c7 Complete the diagram below to show the circuit that could be used to obtain the data

from which the graph was plotted.

(3)

6d7 Sse the graph1 e%plaining your answers1 to

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6i7 determine the emfE of the cellT

...........................................................................................................................

...........................................................................................................................(2)

6ii7 determine the current in the e%ternal circuit when the resistanceR of the e%ternal

circuit is very smallT

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

(2)

6iii7 deduce that the internal resistancer of the cell is about ). E.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(3)

6e7 he ma%imum power dissipated in the e%ternal circuit occurs when the resistance of the

e%ternal circuit has the same value as the internal resistance of the cell. Calculate the

ma%imum power dissipation in the e%ternal circuit.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

(3)(Total 18 marks)

65. his (uestion is about the possibility of generating electrical power using a satellite orbiting the

8arth.

6a7 Definegravitational field strength.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

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48/108

c o n d u c t i n g c a b l e

B

6c7 9n diagram 1 draw an arrow to show the direction of the magnetic force on an electron

in the conducting cable. abel the arrow I.(1)

6d7 >tate an e%pression for the forceF on the electron in terms of B1 v1 e and /1 where0is the

magnitude of the magnetic field strength and eis the electron charge.

.....................................................................................................................................(1)

6e7 Gence deduce an e%pression for the emfE induced in the conducting wire.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(3)

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6f7 he shuttle is in an orbit that is '' !m above the surface of the 8arth. Ssing the

e%pression

G) * g'R

and given thatR : ,.- = )',m andg': )' / !g

)1 deduce that the orbital speedv of the

satellite is


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,

-

'

-

,

* , - ' - , *V

I A

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he component " is now connected across the terminals of a battery of emf ,.' Vand

negligible internal resistance.

6b7 Sse the graph to determine

6i7 the current in component "T

...........................................................................................................................(1)

6ii7 the resistance of component ".

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

A resistorHof constant resistance .'Eis now connected in series with component " as shownbelow.

E

" H

. '

6c7 6i7 9n the graph in 6a71 draw theI-Vcharacteristics for the resistor H.(2)

6ii7 Determine the total potential differenceE that must be applied across component "

and across resistorHsuch that the current through " andHis .' A.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

6d7 6i7 A resistor is to be used as a temperaturemeasuring device. ist twodesirable

properties of such a device.

). .......................................................................................................................

. .......................................................................................................................(2)

6ii7 8%plain how a temperature scale could be constructed for this resistance

thermometer.

...........................................................................................................................

...........................................................................................................................

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...........................................................................................................................

...........................................................................................................................(3)

(Total 14 marks)

67. his (uestion is about electrical components.

6a7 4n the space below1 draw a circuit diagram that could be used to determine the current

voltage 6I-V7 characteristics of an electrical component ".

c o m p o n e n t "

(2)

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he graph below shows theI-Vcharacteristics for the component ".

,

-

'

-

,

* , - ' - , *V

I A

he component " is now connected across the terminals of a battery of emf ,.' V and negligibleinternal resistance.

6b7 Sse the graph to determine

6i7 the current in component "T

...........................................................................................................................(1)

6ii7 the resistance of component ".

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

A resistorHof constant resistance .'Eis now connected in series with component " as shown

below.

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E

" H

. '

6c7 6i7 9n the graph above1 draw theI-Vcharacteristics for the resistor H.(2)

6ii7 Determine the total potential differenceE that must be applied across component "

and across resistorHsuch that the current through " andHis .' A.

...........................................................................................................................

...........................................................................................................................(2)

(Total 9 marks)

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68. 8lectrical circuits

Andrew is set the tas! of measuring the currentvoltage 6I-V7 characteristics of a filament lamp.

he following e(uipment and information are available.

nformation

Battery emf : .' 1 negligible internal resistance

Iilament lamp mar!ed Q 1 '. AR

oltmeter resistance : ' ! 1 reads values between '.' and .'

Ammeter resistance : '.) 1 reads values between '.' and '.5 A

0otentiometer resistance : )''

6a7 Ior the filament lamp operating at normal brightness1 calculate

6i7 its resistanceT

.........................................................................................................................

.........................................................................................................................(1)

6ii7 its power dissipation.

.........................................................................................................................

.........................................................................................................................(1)

Andrew sets up the following incorrectcircuit.

A

6b7 6i7 8%plain why the lamp will not light.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6ii7 >tate the appro%imate reading on the voltmeter. 8%plain your answer.

.........................................................................................................................

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.........................................................................................................................

.........................................................................................................................(2)

6c7 9n the circuit diagram below1 add circuit symbols to show the correct position of the

ammeter and of the voltmeter in order to measure theI-Vcharacteristics of the lamp.

(2)

6d7 9n the a%es below draw a s!etch graph to show theI-Vcharacteristics for this filament

lamp.

I A

' . ?

' .

' . )

' . '

' . ' ) . ' . ' ? . ' - . ' V

(4)

6e7 8%plain the shape of the graph that you have drawn in 6d7.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(2)

Total 14 marks)

69. his (uestion compares the electrical properties of two ) filament lamps.

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A lamp is designed to operate at normal brightness with a potential difference of ) across its

filament. he current in the filament is '.5' A.

6a7 Ior the lamp at normal brightness1 calculate

6i7 the power dissipated in the filament.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(1)

6ii7 the resistance of the filament.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(1)

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4n order to measure the voltagecurrent 6V-I'characteristics of a lamp1 a student sets up

the following electrical circuit.

) b a t t e r y

6b7 9n the circuit above1 add circuit symbols showing the correct positions of an idealammeter andan ideal voltmeter that would allow the V-Icharacteristics of this lamp to be

measured.(2)

he voltmeter and the ammeter are connected correctly in the previous circuit.

6c7 8%plain why the potential difference across the lamp

6i7 cannot be increased to ) .

...........................................................................................................................

...........................................................................................................................(2)

6ii7 cannot be reduced to 3ero.

...........................................................................................................................

...........................................................................................................................(2)

An alternative circuit for measuring the V-Icharacteristic uses apotential divider.

6d7 6i7 Draw a circuit that uses a potential divider to enable the V-Icharacteristics of the

filament to be found.

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(3)

6ii7 8%plain why this circuit enables the potential difference across the lamp to be

reduced to 3ero volts.

...........................................................................................................................

...........................................................................................................................(2)

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he graph below shows the V-Icharacteristic for two ) filament lamps A and B.

)

'' ' . 5 ) . '

c u r r e n t A

0 o t e n t i a ld i f f e r e n c e

l a m p A l a m p B

6e7 6i7 8%plain why these lamps do not obey 9hmLs law.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

6ii7 >tate and e%plain which lamp has the greater power dissipation for a potential

difference of ) .

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(3)

he two lamps are now connected in series with a ) battery as shown below.

l a m p A l a m p B

) b a t t e r y

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6f7 6i7 >tate how the current in lamp A compares with that in lamp B.

...........................................................................................................................

...........................................................................................................................(1)

6ii7 Sse the V-Icharacteristics of the lamps to deduce the total current from the battery.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(4)

6iii7 Compare the power dissipated by the two lamps.

...........................................................................................................................

...........................................................................................................................(2)

(Total 25 marks)

70. his (uestion is about an electric circuit

A particular filament lamp is rated at ) 1 ,.' mA. 4t @ust lights when the potential difference

across the filament is ,.' .

A student sets up an electric circuit to measure theI-Vcharacteristics of the filament lamp.

4n the circuit1 shown below1 the student has connected the voltmeter and the ammeter into the

circuit incorrectl-.

)

A

) ' ' ! >

he battery has emf ) and negligible internal resistance. he ammeter has negligible

resistance and the resistance of the voltmeter is )'' !.

he ma%imum resistance of the variable resistor is )5 .

6a7 8%plain1 without doing any calculations1 whether there is a position of the slider > at

which the lamp will be lit.

...................................................................................................................................

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...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(3)

6b7 8stimate the ma%imum reading of the ammeter.

...................................................................................................................................

...................................................................................................................................(2)

6c7 Complete the circuit diagram below showing the correct position of the voltmeter and of

the ammeter in order to determine theI-Vcharacteristics of the filament lamp.

)

(2)

(Total 7 marks)

71. Geating water electrically

he diagram below shows part of the heating circuit of a domestic shower.

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c o l d w a t e r ) - C

i n s u l a t e d w i r e

- ' w a t e r p i p e

s u p p l y

i n s u l a t e d h e a t i n g e l e m e n t

h o t w a t e r - ' C

Cold water enters the shower unit and flows over an insulated heating element. he heating

element is rated at


64/108

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(2)

6e7 8%plain why1 when the shower unit is switched on1 the initial current in the heatingelement is greater than the current calculated in 6d7.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(2)

6f7 4n some countries1 shower units are operated from a ))' supply. A heating element

operating with a -' supply has resistanceR-'and an element operating from a ))'

supply has resistanceR))'.

6i7 Deduce1 that for heating elements to have identical power outputs

.).'

-'

))'=

R

R

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

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.........................................................................................................................

.........................................................................................................................(3)

6ii7 Ssing the ratio in 6i71 describe and e%plain onedisadvantage of using a ))'

supply for domestic purposes.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

(Total 18 marks)

72. 8lectric circuits

6a7 he diagram below shows the circuit used to measure the currentvoltage 6I-V7

characteristic of an electrical component ".

"

9n the diagram above1

6i7 label the ammeter A and the voltmeter .(1)

6ii7 mar! the position of the contact of the potentiometer that will produce a reading of

3ero on the voltmeter. abel this position 0.(1)

6b7 he graph below shows the currentvoltage 6I-V7 characteristics of two different

conductors " and #.

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' . 5 '

' . - 5

' . - '

' . ? 5

' . ? '

' . 5

' . '

' . ) 5

' . ) '

' . ' 5

' . ' '

) 5 . ') - . ') ? . ') . ') ) . ') ' . 'N . '* . '< . ', . '5 . '- . '? . ' . ') . '' . '

#"

I A

V

6i7 >tate the value of the current for which the resistance of " is the same as the

resistance of # and determine the value of this resistance

CurrentV .....................................................................................................

HesistanceV .....................................................................................................(2)

6ii7 Describe and suggest an e%planation for theI-Vcharacteristic of conductor #.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(3)

6c7 he two conductors " and # are connected in series with a cell of negligible internal

resistance. he current in the conductors is '.' A.

Sse the graph in 6b7 to determine

6i7 the resistance of # for this value of currentT

.........................................................................................................................

.........................................................................................................................

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(1)

6ii7 the emf of the cell.

.........................................................................................................................

.........................................................................................................................

(2)(Total 10 marks)

73. his (uestion is about electric current and the effects of electric current.

8lectric current

6a7 he diagram below shows the circuit used to measure the currentvoltage 6I-V7

characteristic of an electrical component ".

"

9n the diagram above1

6i7 label the ammeter A and the voltmeter T(1)

6ii7 mar! the position of the contact of the potentiometer that will produce a reading of

3ero on the voltmeter. abel this position 0.(1)

6b7 he graph below shows the currentvoltage 6I-V7 characteristics of two different

conductors " and #.

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' . 5 '

' . - 5

' . - '

' . ? 5

' . ? '

' . 5

' . '

' . ) 5

' . ) '

' . ' 5

' . ' '

) 5 . ') - . ') ? . ') . ') ) . ') ' . 'N . '* . '< . ', . '5 . '- . '? . ' . ') . '' . '

#"

I A

V

6i7 >tate the value of the current for which the resistance of " is the same as the

resistance of # and determine the value of this resistance.

CurrentV ....................................................................................................

Hesistance ....................................................................................................

....................................................................................................(2)

6ii7 Discribe and suggest an e%planation for theI-Vcharacteristic of conductor #.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(3)

6c7 he two conductors " and # are connected in the circuit as shown below.

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)

F

"

#

he cell has emf ) and negligible internal resistance. he resistor F has resistance R

and the potential difference across the conductors " and # is 5.' .

6i7 Sse the graph in 6b7 to determine the total current in the circuit.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6ii7 Determine the resistanceRof the resistor1.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6iii7 Determine the total resistance of the parallel combination of " and #.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

8lectromagnetic effects associated with steady electric currents

6d7 A long vertical wire passes through a sheet of cardboard that is held hori3ontal. A small

compass is placed at the point 0 and the needle points in the direction shown.

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c a r d b o a r d s h e e t d i r e c t i o n o f c o m p a s s n e e d l e

0

A current is passed through the wire and the compass needle now points in a direction

that ma!es an angle of 'to its original direction as shown below.

0

d i r e c t i o n o f c o m p a s sn e e d l e w i t h c u r r e n t i n w i r e

o r i g i n a l d i r e c t i o n o fc o m p a s s n e e d l e

? ' c a r d b o a r d s h e e t

6i7 Draw an arrow on the wire to show the direction of current in the wire. 8%plain

why it is in the direction that you have drawn.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6ii7 he magnetic field strength at point 0 due to the current in the wire is0Wand the

strength of the hori3ontal component of the 8arthLs magnetic field is08.

Deduce1 by drawing a suitable vector diagram1 that

08:0Wtan ,'.

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.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

8lectromagnetic effect due to timechanging currents

6e7 >tate

6i7 IaradayLs law of electromagnetic inductionT

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6ii7 en3Ls law.

.........................................................................................................................

.........................................................................................................................

(1)

6f7 A long solenoid is connected in series with a battery and a switch >. >everal loops of wire

are wrapped around the solenoid close to its midpoint as shown below.

>

he ends of the wire are connected to a high resistance voltmeter that has a centre 3ero

scale 6as shown in the inset diagram7.

Describe1 and e%plain1 the deflection on the voltmeter when

6i7 the switch > is closedT

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DescriptionV .................................................................................................

.................................................................................................

.................................................................................................

.................................................................................................

8%planationV .................................................................................................

.................................................................................................

.................................................................................................

.................................................................................................(4)

6ii7 the switch > is reopened a short time after being closed.

DescriptionV .................................................................................................

.................................................................................................

.................................................................................................

.................................................................................................

8%planationV .................................................................................................

.................................................................................................

.................................................................................................

.................................................................................................(4)

(Total 28 marks)

74. >tatic electricity

6a7 By reference to the movement of charge in a metal and in plastic1 e%plain the electrical

properties of conductors and insulators.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(3)

6b7 A goldleaf electroscope is positively charged.

6i7 9utline why there is no electric field inside the metal cap of the electroscope.

.........................................................................................................................

.........................................................................................................................

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.........................................................................................................................(2)

6ii7 A student touches the metal cap of the electroscope. Describe the movement of

charge that occurs.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

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Current electricity

6c7 4n order to investigate the variation of the currentIin a variable resistor with the potential

difference Vacross it1 a student set up the following circuit.

A

he variation of the currentIwith Vis shown below.

V ,

-

'

' ) ? -I A

Sse the graph to deduce that1 for the battery1

6i7 its emf is -.5 .

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

(2)

6ii7 its internal resistance is ). .

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6d7 he battery in 6c7 is to be used as the power source for an electrical device. he device is

rated as '.* 1 ).5 A.

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Complete the circuit below to show how the battery may be connected so that the device

operates normally. Calculate the value of any other component you may use.

d e v i c e ' . * 1 ) . 5 A

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(4)

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6e7 An electric heater contains a number of similar heating elements1 connected as shown to

a supply of Vvolts. he switches >)and >are shown QopenR.

' + V

> )

>

8ach heating element dissipates powerPwhen connected to a supply of Vvolts. he

resistance of each element may be considered to be constant.

Complete the table below to give the total power dissipated1 in terms of P1 for the

switches in the positions indicated.

!witc# !1 !witc# !2 Total 'ower

closed closed

closed open

open open

(3)

(Total 18 marks)

75. 8lectricity

>tatic electricity

6a7 By reference to the movement of charge in a metal and in plastic1 e%plain the electrical

properties of conductors and insulators.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(3)

6b7 A goldleaf electroscope is positively charged.

6i7 8%plain why the electroscope has an electric potential with respect to 8arth.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6ii7 9utline why there is no electric field inside the metal cap of the electroscope.

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.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6iii7 A student touches the metal cap of the electroscope. Describe the movement of

charge that occurs.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

Current electricity

6c7 4n order to investigate the variation of the currentIin a variable resistor with the potential

difference Vacross it1 a student set up the following circuit.

A

he variation of the currentIwith Vis shown below.

V ,

-

'

' ) ? -

I A

Sse the graph to deduce that1 for the battery1

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6i7 its emf is -.5 T

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

(2)

6ii7 internal resistance is ). .

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................(2)

6d7 he battery in 6c7 is to be used as the power source for an electrical device. he device is

rated as '.* 1 ).5 A.

Complete the circuit below to show how the battery may be connected so that the device

operates normally. Calculate the value of any other component you may use.

d e v i c e

' . * 1 ) . 5 A

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(4)

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6e7 An electric heater contains a number of similar heating elements1 connected as shown to

a supply of Vvolts. he switches >)and >are shown QopenR.

' + V

> )

>

8ach heating element dissipates powerPwhen connected to a supply of Vvolts. he

resistance of each element may be considered to be constant.

Complete the table below to give the total power dissipated1 in terms of P1 for the

switches in the positions indicated.

!witc# !1 !witc# !2 Total 'ower

closed closed

closed open

open open

(3)

(Total 20 marks)

76. 8lectrical conduction

4n a copper wire the number of conduction electrons is e(ual to the number of copper atoms in

the wire.

6a7 >tate what is meant by cond%ction electrons.

...................................................................................................................................

...................................................................................................................................(1)

6b7 6i7 he density of copper is *.N )'!g m

and its molar mass is ,- g. Deduce that

the number of moles of copper in a volume of ).' mis ).- )'

5.

.........................................................................................................................

..........................

Documents

Electricity Practice