Sapkal Knowledge Hub

Kalyani Charitable Trust’s

Late G. N. Sapkal College of Engineering

Multiple Choice Questions

Engineering Physics - unit I

Engineering Physics 1

Interference and Diffraction

1. Interference of light is evidence that :

A. The speed of light is very large

B. light is a transverse wave

C. light is electromagnetic in character

D. Light is a wave phenomenon

2. In Newton's Ring experiments , the diameter of bright rings is proportional

to

A. Square root of Odd Natural numbers

B. Natural Number

C. Even Natural Number

D. Square root of natural number

3. In Newton's Ring experiments , the diameter of dark rings is proportional

to

A. Odd Natural numbers

B. Natural Number

C. Even Natural Number

D. Square root of natural number

4. A wavelength is commonly measured in which one of the following units?

A. Radians

B. Angstroms

C. Electron volts

D. Seconds

5. Extended source is needed in

A. Young's double slit experiment

B. Bi prism Experiment

C. Newton’s Ring Experiment

D. None of them

6. The phenomenon of diffraction can be understood using

A. Huygens principle

B. Fraunhofer

C. Uncertainty principle

D. Fresnel

Engineering Physics 2

7. Whose principle or law states that each point on a wave front may be

considered a new wave source? Is it:

A. Snell's Law

B. Huygens’s Principle

C. Young's Law

D. Hertz's Law.

8. What is the name of the process whereby waves travel around corners

and obstacles in their paths?

A. Reflection

B. Refraction

C Interference

D. Diffraction

9. In Fraunhofer diffraction, the incident wave front should be …..

A. elliptical

B. Plane

C. Spherical

D. Cylindrical

10. significant diffraction of X ray can be obtained

A. By a single slit

B. By a double slit

C. By diffraction

D. By Atomic crystal

11. A slit of width ‘a’ is illuminated by white light. For what value of ‘a’ will

the first minimum for red light fall at an angle of 300 wavelength of red

light is 6500 A0

A. 1.1 x 10 -3 cm

B. 1.4 X 10 -4 cm

C. 1.3 X 10 -4 cm

D. 1.6 X 10 -4 cm

12. The wave nature of light is demonstrated by which of the following?

A. The photoelectric effect

B. Color

C. The speed of light

D. Diffraction

Engineering Physics 3

13. A grating has 6000 lines per cm. How many orders of light of wavelength

4500 A 0 can be seen?

A. 1

B. 2

C. 3

D. 4

14. Find the maximum value of resolving power of a grating 3 cm wide having

5000 lines per cm, if the wavelength of light used is 5890 A0.

A. 40000

B. 45000

C. 4500

D. 5000

15. In Fresnel diffraction

A. source of light is kept at infinite distance from the aperture

B. source of light is kept at finite distance from the aperture

C. Convex lens used

D. aperture width is selected so that it can acts as a point source

16. in the diffraction pattern using circular aperture , when the screen is brought

towards the aperture

A. the intensity of the screen is gradually increases.

B. the intensity of the screen is gradually decreases

C. the light is found to focus only to a fixed distance

D. Many points are observed where greater intensity is found

17. To find prominent diffraction , the size of diffraction object should be

A. greater than wavelength of light used

B. comparable to order of wavelength of light

C. less than wavelength of light used

D. none of these.

18. A color with a wavelength longer than that of yellow is:

A. Red

B. Blue

C. Violet

D. Green

Engineering Physics 4

19. In plane transmission grating, the angle of diffraction for second order

maxima for wavelength 5 x 10 -5 cm is 30 0. Calculate the number of lines

in one centimeter of the grating surface.

A. 1000 lines/cm

B. 5000 lines/cm

C. 500 lines/cm

D. 10000 lines/cm

20. What is the highest order spectrum which may be seen with monochromatic

light of wavelength 5000 A0 by means of diffraction grating with 5000

lines/cm?

A. 2

B. 4

C. 8

D. 16

21. The first reflecting telescope was built by:

A. Galileo

B. Copernicus

C. Tyco Brahe

D. Isaac Newton

22. The critical angle for water (n = 1.33) in air is

A. 33° B. Not defined C. 49 0 D. 24

0

23. The dark lines constituting the absorption spectrum exhibited by sunlight

are frequently called:

A. Fresnel lines

B. Fraunhofer lines

C. Fermi lines

D. Franklin lines

24. A beam of white light is passed through a diffraction grating and the

resulting spectrum is allowed to fall on a screen. Which one of the

following is the color of light that undergoes the greatest deviation from its

original direction? Is it:

A. Red

B. yellow

C. Blue

D. violet

Engineering Physics 5

25. When a light ray travelling in glass is incident on an air surface,

A. it will refract away from the normal

B. some of the light may be reflected

C. all of the light may be reflected

D. two of A, B, and C

E. all of A, B, and C

26. Light is

A. an electromagnetic wave

B. a form of energy visible to the human eye

C. the same type of energy as an X ray

D. the same type of energy as a radio wave

E. all of the above

27. What is the speed of light in glycerin (n = 1.47) expressed in terms of the

speed of light in a vacuum?

A. 2.04c

B. 1.47c

C. 0.680c

D. 1.00c

28. Which of the following does NOT travel in a vacuum?

A. Radio waves

B. Gamma rays

C. Magnetic waves

D. Sound waves

29. The region of the electromagnetic spectrum immediately above the

frequencies to which the human eye is sensitive is called:

A. I r

B. ultra-violet

C. r f

D. gamma ray

30. A beam of light is incident on a large block of glass. The index of refraction

of the glass is greater than one. Is the wavelength of the light in the glass?

A. Longer than

B. Shorter than

C. The same as the wavelength of the light in the air?

D. None of above

Engineering Physics 6

31. The angle of incidence for a wave

A. can be measured between the incident ray and the normal

B. can be measured between the incident wave front and the boundary

C. is equal to the angle of reflection

D. all of the above

32. In Michelson ‘s interferometer 100 fringes cross the field view when the

movable mirror is displaced through 0.0248 mm. Calculate the wavelength

of monochromatic light used

A. 5896 A 0 B.5890 A

0 C.4000 A

0 D. 4890 A

0

33. In Newton's ring experiment, the diameter of the 15 th

ring was found to be

0.590 and that of the 5 th

ring was 0.336 cm. If the radius of Plano convex

lens is 100 cm, compute the wavelength of light used.

A. 5885 A 0 B. 5880 A

o C. 5890 A

o D.5850 A

o

34. Second glass plate in Michelson ‘s Interferometer is known as

A. Extra glass plate C. Simple Glass Plate

B. Compensating glass plate D. None of these

35. In reflected light the central fringes of Newton's ring is

A. dark B. Bright C. Uniform D. Non uniform

36. A phase difference ∏ between two interfering beams is equivalent to the

path difference

A. 2 λ B. λ C. λ/2 D. λ/4

37. Which of the following does not support the wave nature of light

A. Interference C. Polarisation

B. Compton effect D. Diffraction

38. Colors in thin films are because of

A. Dispersion C. Interference

B. Compton effect D. Diffraction

39. As a wave travels down a spring, the amplitude slowly decreases. Why does

this occur?

A. The law of conservation of energy does not apply to waves.

B. The energy is spread out along the entire length of the spring.

C. The wave slows down as it travels along the spring.

D. Some energy is lost due to friction as the particles in the spring

rub against each other.

E. all of the above

Engineering Physics 7

40. For single slit Diffraction, the path difference between the two ends of the

slit is

A. Δ = a Sin θ B. Δ = a Cos θ C. Δ = Cos θ D. Δ = 0

41. In a longitudinal wave,

A. The particles move parallel to the direction of the wave motion.

B. The particles move perpendicular to the direction of the wave motion.

C. Energy causes the particles to move forward with the wave.

D. Energy is propagated by crests and troughs.

42. The speed of any mechanical wave as it propagates through a medium is

dependent mainly on the

A. frequency of the wave source

B. wavelength

C. period of the wave

D. type of medium through which the wave travels

E. amplitude

43. In a Young's double-slit experiment the center of a bright fringe occurs

wherever waves from the slits differ in the distance they travel by a multiple

of:

A. a fourth of a wavelength

B. a half a wavelength

C. a wavelength

D. three-fourths of a wavelength

44. Light enters air from water. The angle of refraction will be

A. Greater than the angle of incidence.

B. Equal to the angle of incidence.

C. Less than the angle of incidence.

D. None of these

45. Rainbow is due to

A. absorption of sunlight in minute water droplets

B. diffusion of sunlight through water droplets

C. ionization of water deposits

D. refraction and reflection of sunlight by water droplets

Engineering Physics 8

46. The speed of light in material A is 1.25 times as large as it is in material B.

What is the ratio of the refractive indices, µA /µB of these materials?

A.1.50 B.1.00 C.0.800 D.1.25

47. Radio telescopes are better than optical telescopes because

A. they can detect faint galaxies which no optical telescope can

B. they can work even in cloudy conditions

C. they can work during the day and night

D. All of the above

48. On a rainy day, small oil films on water show brilliant colors'. This is due to

A. dispersion B. interference C. diffraction D. Polarization

49. The critical angle for a beam of light passing from water into air is 48.8 °.

This means that all light rays with an angle of incidence greater than this

angle will be

A. absorbed B. totally reflected

C. Partially reflected and partially transmitted

D. Totally transmitted

50. The principle on which fiber optics is based is

A. refraction C. polarization

B. Dispersion. D. Total internal reflection

51. A monochromatic (single frequency, single wavelength) light ray in air

(n = 1) enters a glass prism (n = 1.5). In the glass prism

A. Both the frequency and the wavelength are the same as in air

B. The frequency is the same, but the wavelength is greater than in air.

C. The frequency is the same, but the wavelength is smaller than in air.

D. The wavelength is the same, but the frequency is greater than in air.

E. The wavelength is the same, but the frequency is smaller than in air.

52. An index of refraction less than one for a medium would imply

A. That the speed of light in the medium is the same as the speed of

light in vacuum

B. That the speed of light in the medium is greater than the speed of

light in vacuum

C. Refraction is not possible

D. Reflection is not possible

Engineering Physics 9

53. The characteristic that distinguishes a laser beam from an ordinary light

beam is:

A. The greater frequency of the laser beam

B. The coherence of the laser beam

C. The color of the laser beam

D. The greater polarization of the laser beam

54. Light travels fastest

A. In a vacuum

B. through water

C. Through glass

D. through diamond

55. For all transparent material substances, the index of refraction

A. A.is less than 1

B. B.is greater than 1

C. C.is equal to 1

D. Could be any of the given answers; it all depends on optical density

56. An index of refraction less than one for a medium would imply

A. That the speed of light in the medium is the same as the speed of

light in vacuum

B. That the speed of light in the medium is greater than the speed of

light in vacuum

C. Refraction is not possible

D. Reflection is not possible

57. Coherent light of a single frequency passes through a double slit with a

separation d, to produce a pattern on a screen as distance D from the slits.

What would cause the separation between adjacent minima on the screen to

increase?

A. A. increase the index of refraction of the medium in which the

setup is immersed

B. increase the separation d between the slits

C. increase the distance

D. increase the frequency of the incident light

Engineering Physics 10

58. When light passes from air into water, the frequency of the light remains

the same. What happens to the speed? And the wavelength of light as it

crosses the boundary in going from air into water?

Speed Wavelength

A. Increases Remains the same

B. Remains the same Decreases

C. Remains the same remains the same

D. Decreases Increases

E. Decreases Decreases

59. Optical fiber works on the

A. principle of refraction

B. total internal reflection

C. scattering

D. interference

60. The fringe width and the angle of wedge are related to

A. β=λ/2θ

B. θ =λ/2 β

C. β=λ/θ

D. λ= β/2θ

61. A diffraction grating is optically equivalent to a multiple slit system in

which the number of slit , N is typically

A.2000/cm B.3000/cm

C.5000/cm D.1000/cm

62. In Rayleigh law of scattering ,The intensity of scattered light is

proportional to

A. λ

B. λ -2

C. λ -4

D. λ-1

63. Resolving power of grating is given by

A. λ/2

B. λ/dλ

C. dλ/λ

D. none of these

Engineering Physics 11

64. In Newton’s rings the central spot is __________. A. Always bright

B. always dark C. can be bright or dark

D. of blue color 65. The conditions for the production of constructive and destructive

interference are reversed due to the fact that on striking the thin film -------. A. Two rays of splitted light undergo phase change of 180°

B. One of two rays of splitted light undergo phase change of 180°

C. Light is diffracted, light is polarized

66. When electromagnetic waves strike the boundary of denser medium they are __________.

A. Reflected, in phase B. Reflected out of phase by 180°

C. reflected, they are completely absorbed 67. In Michelson interferometer semi silvered mirror is used

To obtain __________. A. Thin film interference

B. Phase coherence C. mono chromatic light

D. colored fringe 68. Fresnel’s type diffraction is observed when __________.

A. Only screen is placed at finite distance

B. Only source is placed at finite distance C. Both source and screen are at finite distance

D. Neither source nor screen is at finite distance 69. Fraunhofer diffraction is observed when __________.

A. Only screen is placed at finite distance B. source is placed at finite distance

C. neither source nor screen is at finite distance D. None of these

70. In Fraunhofer diffraction wave front used is __________. A. Spherical B. Circular C. Plane D. Conical

71. In diffraction pattern of monochromatic light the bright bands formed are __________.

A. of uniform intensity

B. of non-uniform intensity C. of uniform width

D. is of different colors

Engineering Physics 12

72. The points of constructive interference of light are__________.

A. Always bright B. may be bright or dark

C. always dark D. neither bright nor dark

73. The diffraction observed by diffraction grating can also be Termed as __________.

A. Single slit diffraction B. double slit Diffraction

C. multiple Slit Diffraction D. Fresnel’s Diffraction

74. The grating used to observe, diffraction of visible light can have approximately __________.

A.300 lines per cm B.3000 lines per cm, C. 15000 lines per cm

D. 30 lines per cm 75. X-ray diffraction can be observed by using __________.

A. Diffraction Grating B. Rock salt crystal

C. Convex lens D. Michelson’s interferometer

76. The phenomenon of Newton’s rings can be used to check the __________. A. Wavelength of monochromatic light

B. phase coherence of two sources C. flatness of any glass surface

D. velocity of light 77. Two sources of light are said to be coherent if __________.

A. they produce waves of the same wave length

B. they have the same amplitude of vibration C. they produce waves in the medium simultaneously

D. they produce waves of the same amplitude 78. as the order increases, the width of a dark band in diffraction

Patterns __________. A. Increases

B. Decreases C. Does not change

D. becomes infinity

Engineering Physics 13

79. The path difference corresponding to a phase difference of π radian is __________.

A.2λ B .λ/2

C .λ /4 D. λ

80. __________ of the following phenomenon cannot be explained on the particle nature of light.

A. Photo Electric Effect B. Compton’s Effect

C. Pair Production D. Interference

81. Fringe spacing is defined as the distance between two Consecutive __________.

A. Crests B. Bright fringes only C. Dark fringes only

D. Bright or dark fringes 82. If we narrow the distance between two slits in Young’s experiment the

fringes width __________. A. Increases

B. Decreases C. Remains same

D. becomes zero 83. When Newton’s rings interference pattern is viewed from above by means

of reflected light, the central spot is __________. A. Dark

B. Multi colored C. Bright D. None of these

84. There are two types of diffraction Fresnel and __________. A. Michelson

B. De Broglie C. Fraunhofer

D. Huygens 100. Diffraction is special type of __________.

A. Reflection B. Refraction

C. Interference D. Polarization

Engineering Physics 14

101. Interference in thin film is mainly because of

A. Division amplitude B. Division of wave fronts

C. Addition of amplitude D. Addition of wave fronts

102. The interference in thin films is because A. The film reflects some light

B. The film is thin enough so that refracted ray is close to reflected ray C.

D. All of above 103. When a light wave suffers reflection at the interface between air and glass

medium, the change of phase of the reflected wave in air is equal to A. 0 B. π

C.2 π D.π /2 104. A thin film having thickness t<<λ is seen in white light. It will appear A. White B. Red

C. Black D. Violet 105. A wedge shaped thin has

A. Non-uniform thickness B. Zero thickness at one end and it increasing towards other end

C. Zero thickness at both ends D. Thickness increase and decrease alternately

106. What is the nature of interference pattern for thin film of wedge shaped A. Concave outside B. Convex outside

C. Equally spaced D. Concave inside 107. Interference pattern is observed in wedge-shaped film for monochromatic

light. Now monochromatic light is replaced by white light. What will be the effect on interference pattern?

A. It will turn to dark B. It will turn to bright

C. Bands will disappear D. It will be a mixture of all colors 108. Newton’s light illustrate the phenomenon of

A. Interference B. Diffraction C. Dispersion D. Polarization

109. In Newton’s rings experiment, if we reduce the radius of curvature of Plano

convex lens to zero, what will be effect on Newton’s rings? A. They will become brighter B. They will become darker

C. They will disappear D. They will be more dense

Engineering Physics 15

110. Why in Newton’s rings the center spot is always dark? A. The thickness of the film is zero at center

B. The path difference between incident ray and reflected ray is ½wavelength C. The incident ray and reflected ray undergo destructive interference

D. All of above

111. Antireflection coating is helps in which case of the following?

A. Minimizing the reflection of light from top surface B. To absorb and control the amount of light entering into the medium

C. To allow maximum light to reflect from top surface D. To allow minimum light to enter into the medium

112. What should be the relation between refractive indices for antireflection

coating made over a glass surface? A. Bair > Bfilm > Bglass

B. Bair < Bfilm < Bglass C. Bair > Bfilm < Bglass D. Bair < Bfilm > Bglass

113. In reference with antireflection coating which of the following statement is

true? A. Thickness of the film should be changed for light of same wavelength but different

intensity B. Thickness of the film need not be changed for light of same wavelength but

different intensity

C. Thickness of the film should be increased for light of same wavelength but higher intensity

D. Thickness of the film should be decreased for light of same wavelength but higher intensity

114. Which of the following condition is essential for observing Fraunhofer diffraction?

A. Source must be close to slit and screen should be at infinite distance B. Both source and screen must be close to slit

C. Source must be at infinity and screen should be close to the slit D. Both source and screen must be at infinity

115. In diffraction Fraunhofer diffraction pattern due to single slit central maxima

is formed at center because: A. Lens focuses all the diffracted rays at the centre of the slit

Engineering Physics 16

B. Slit focuses all the diffracted rays at the centre of the slit C. Light rays focused at the centre of the screen undergo constructive interference

D. Slit and lens both combined focuses the rays at the centre of the slit

116. In Fraunhofer diffraction pattern for single slit, a central maximum is obtained when angle of diffraction q is equal to zero. What it actually indicates?

A. All the diffracted rays are parallel and focused by slit at a single point on screen

B. All the diffracted rays are perpendicular and focused by slit at a single point on screen C. The rays are diffracted by the slit in all the directions

D. The rays are reflected by the slit

117. The condition for minima in Fraunhofer diffraction for single slit is asinθ = mλWhat is ‘θ’?

A. Angle of incidence of incident rays at the slit

B. Angle at which diffracted rays strikes the screen C. Angle between slit and screen

D. Angle of diffraction at which rays are diffracted at slit 118. How the intensity of secondary maxima varies in case of

Fraunhofer diffraction pattern for single slit? A. Intensity of secondary maxima decreases on either sides

B. Intensity of secondary maxima remains constant on either side C. Intensity increases and decreases alternately

D. Intensity of secondary maxima increases on either sides

119. Fraunhofer diffraction at a Plane Grating What is the meaning of grating element for a diffraction grating?

A It is the width of a single slit

B. It is the width of the opaque space C. It is the distance between two slits

D. It is the width of diffraction grating

120. What is the effect of increasing the number of slits on the intensity of Central maxima of diffraction pattern of a diffraction grating?

A. Intensity of central maxima will decrease B. Intensity of central maxima will increase

C. There will not be any effect D. Diffraction pattern will disappear

121. The condition for maxima for Fraunhofer diffraction due to a slit is

d sinθ = nλ ,where d=grating element = (a+b). What is the effect on diffraction pattern if d is reduced?

Engineering Physics 17

A. The separation between maxima and minima will increase B. The separation between maxima and minima will decrease

C. There will not be any effect on diffraction pattern D. Maxima and minima will merge into each other

122. Diffraction due to circular aperture If a light passes through a small pinhole,

and incident on a screen. What will be observed on the screen? A.A sharp bright point of the width equal to width the pinhole

B. A bright point of the width equal to width the pinhole but of less intensity C. A bright ring at the centre surrounded by alternate dark and bright

rings D. A diffused bright point

123. What is true for intensity of scattered light according to Rayleigh’s law?

A. The intensity for scattering for light of largest wavelength more B. The light of smallest wavelength will be scattered more C. All the wavelengths are scattered equally

D. Intensity of light is not affected by scattering

124. The number of lines on plane gratings is 5000. If it is illuminated by a wavelength of light 6000 A

0, how many orders will be visible?

A. 3 B. 3.33 C. 4 D. 2.0

125. A film is said to be thin if its thickness is

(a) Much smaller than wavelength of light

(b) Comparable with one wavelength of light

(c) Of the order of nanometer (10-9

m) (d) Of the order of Pico meter (10

-12 m)

126. To observe interference in thin films with a light of wavelength λ, the thickness of the film

(a) Should be much smaller than λ

(b) Should be a few thousand times of λ

(c) Should be of the order of λ

(d) Should be of the order of nanometer 127. Interference in thin film is mainly because of (a) Division amplitude

(b) Division of wave fronts (c) Addition of amplitude

(d) Addition of wave fronts

Engineering Physics 18

128. Which of the following phenomenon produces colors in soap bubble?

(a) Interference (b) Diffraction (c) Polarization (d) Dispersion

129.The interference in thin films is because

(a) The film reflects some light (b) The film is thin enough so that refracted ray is

close to reflected ray

(c) The reflected ray undergo path change of λ/2

(d) All of above

130. If you look perpendicular at thin film and move yourself away

from the film (staying perpendicular to the film), you will notice (a) Reflected light becomes brighter and brighter (b) Reflected light becomes darker and darker

(c) Reflected light alternates between darker and brighter (d) None of the Above

131. When a light wave suffers reflection at the interface between air and glass medium, the change of phase of the reflected wave in air is equal to (a) 0 (b) π

(c) 2π (d) π/2 132. When a light wave suffers reflection at the interface between air and glass medium, the change of wavelength of the reflected wave in air is equal to (a) 0 (b) λ/2

(c) λ (d) 2λ 133. A thin film having thickness t<<λ is seen in white light. It will appear (a) White (b) Red (c) Black (d) Violet

134.

In interference experiment, monochromatic light is replaced by white light, we will see

(a) Uniform illumination of screen (b) Uniform darkness on the screen

(c) Equally spaced dark and white bands (d) Few colored bands and then general illumination

Engineering Physics 19

135. A thin film is observed in white light. The color of the film seen at a particular point depends upon

(a)Location of observer (b)Width of the source (c) Distance of the source

(d) Brightness of the source

136.

In interference experiment, by keeping all other parameters constant, if you see the thin film interference from different angles, you will observe

(a)Uniform illumination of screen (b) Uniform darkness on the screen (c) Equally spaced dark and white bands (d) Few colored bands and then general illumination

137. A wedge shaped thin has

(a) Non-uniform thickness (b) Zero thickness at one end and it increasing towards other end

(c) Zero thickness at both ends

(d) Thickness increase and decrease alternately

138. In wedge shaped film the interference pattern has nature

(a) Parallel to the end where thickness is non-zero (b) Perpendicular to contact edge

(c) Parallel to contact edge (d) Perpendicular to the end where thickness is non-zero

139. What is the nature of interference pattern at the contact edge of wedge

shaped film (a) Always bright

(b) Always dark (c) Bright or dark depending upon the thickness of other end

(d) Bright or dark depending upon the wavelength of the light 140. What is the nature of interference pattern for thin film of wedge shaped

(a) Concave outside (b) Convex outside (b) Equally spaced (d) Concave inside

141.

In thin film of wedge shaped, by keeping all other parameters constant, if

only wavelength of incident light is increased. What will be the effect on

Engineering Physics 20

bandwidth? (a) Bandwidth increases (b) Bandwidth decreases

(c) Bands will merge (d) There will not any effect

142.

Interference pattern is observed in wedge-shaped film and bandwidth is noted. Now the thin film is replaced by the film of higher refractive index.

What will be the effect on bandwidth? (a) Bandwidth increases (b) Bandwidth decreases

(c) Bands will merge (d) There will not any effect

143. Interference pattern is observed in wedge-shaped film and bandwidth is

noted. Now the angle of wedge is reduced. What will be the effect on bandwidth?

(a) Bandwidth increases (b) Bandwidth decreases (c) Bands will disappear (d) There will not any effect

144.

Interference pattern is observed in wedge-shaped film and bandwidth is noted. Now the angle of wedge is reduced to zero. What will be the effect on

Bandwidth? (a) Bandwidth increases (b) Bandwidth decreases

(c) Bands will disappear (d) There will not any effect

145.

Interference pattern is observed in wedge-shaped film for monochromatic light. Now monochromatic light is replaced by white light. What will be the

effect on interference pattern? (a) It will turn to dark (b) It will turn to bright

(c) Bands will disappear (d) It will be a mixture of all colors 146. The Radius (or diameter) of dark rings in Newton’s rings is

(a) Directly proportional to the square root of odd numbers (b) Inversely proportional to the square root of natural numbers

(c) Directly proportional to the square root of even numbers

(d) Directly proportional to the square root of natural numbers

147. The Radius (or diameter) of bright rings in Newton’s rings is

(a) Directly proportional to the square root of odd numbers (b) Inversely proportional to the square root of natural numbers

(c) Directly proportional to the square root of even numbers (d) Directly proportional to the square root of natural numbers

Engineering Physics 21

148. In Newton’s rings experiment, if monochromatic source of light is replaced

by another monochromatic source of higher wavelength. What will be the effect on radius (or diameter)?

(a) Radius (or diameter) will decrease (b) Radius (or diameter) will increase

(c) There will be no effect

(d) Radius (or diameter) will remain constant but there will be more

brightness

149. Newton’s rings experiment is performed with air gap between lens and plate.

Now that gap is filled with water. What will be effect on radius

(or diameter)?

(a) Radius (or diameter) will remain constant but there will be more

brightness (b) Radius (or diameter) will increase (c) Radius (or diameter) will decrease

(d) There will be no effect

150. Newton’s rings experiment is performed and radius (or diameter) is calculated. Now Plano-convex lens is replaced with another Plano-convex

lens of greater Radius of curvature. What will be effect on radius (or diameter)?

(a) Radius (or diameter) will remain constant but there will be more brightness

(b) Radius (or diameter) will increase (c) Radius (or diameter) will decrease

(d) There will be no effect

151. In case of thin film of non-uniform thickness, when illuminated with white

light, the film appears colored. This is due to change of what factor? (a) Conditions for path difference at different points of film

(b) Change in optical path difference at different points of film (c) Thickness of film is different at different points of film

(d) All of above

152. Newton’s light illustrate the phenomenon of (a) Interference (b) Diffraction

(c) Dispersion (d) Polarisation

Engineering Physics 22

--------------------------------------------The End-------------------------------------

153. In Newton’s rings experiment, if we reduce the radius of curvature of Plano-

Convex lens to zero, what will be effect on Newton’s rings?

(a)They will become more bright (b)They will become more dark

( c)They will disappear (d) They will be more dense

154. Why in Newton’s rings setup, the beam splitter (mirror) is kept at 45

0?

(a) It allows light rays to incident at 45

0 over the top surface of Plano-

convex lens

(b) It allows light rays to incident uniformly over the top surface of Plano-convex lens

(c) It allows light rays to incident parallel over the top surface of Plano-convex lens

(d) It allows light rays to incident at 900 over the top surface of Plano-

convex lens

155. Newton’s rings are formed because of interference between the light

Reflected from

(a) Upper surface of Plano-convex lens and lower surface of plane glass

plate

(b) Lower surface of Plano-convex lens and upper surface of plane glass

plate (c) Lower and upper surface of Plano-convex

(d) Lower and upper surfaces of plane glass plate

Engineering Physics 23

1.