Physics Lights and Optics Online Mcqs Test

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Question 1

1. The light produced by a laser is all the following except

Answer

In the form of a narrow beam

Answer

Electromagnetic

Answer

Incoherent

Answer

Monochromatic

Question 2

2. Huygen’s wave fronts which sends out secondary wavelets with a speed equal to

Answer

Speed of propagation less than the wave

Answer

Speed of propagation greater than wave

Answer

Speed of propagation of the wave

Question 3

3. Polarization occurs only in ________ waves

Answer

Mechanical waves

Answer

Transverse

Answer

Matter waves

Answer

Longitudinal

Question 4

4. An oil surface floating on water surface exhibits beautiful colour patter, which is due to

Answer

Interference of light

Answer

Reflection of light

Answer

Diffraction of light

Answer

None of these

Question 5

5. When the two surfaces of a thin film are parallel and the light is incident at a certain angle, _________ fringes are formed.

Answer

Elliptical

Question 6

6. Which of the following has least wavelength?

Answer

Ultra-violet rays

Answer

Cosmic-rays

Question 7

7. The phenomenon of bending of light waves around the edges of an obstacle or a narrow opening is called.

Answer

Transmission

Answer

Reflection

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Diffraction

Answer

Refraction

Question 8

8. Wavelength of light of frequency 100 Hz is

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2 x 10⁶ m

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4 x 10⁶ m

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5 x 10⁶ m

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3 x 10⁶ m

Question 9

9. The setting of Newton’s rings is

Answer

A Plano convex lens and simple glass sheet

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A Plano convex lens (long focal length) and the plane of glass plate

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A Plano convex lens and the plane glass plate

Answer

None of these

Question 10

10. Diffraction fringes are

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Equally spaced

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They are adjacent with no space in between

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Distance between them increases

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Distance between then decreases

Question 11

11. Which of the following is conserved when light waves interfere?

Question 12

12. Can two head lights of car can produce interference

Answer

Partly produce interference

Answer

None of these

Question 13

13. A spectrum which contains all wavelengths without any break is called

Answer

Line spectrum

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Continuous emission spectrum

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Emission spectrum

Answer

All of these

Question 14

14. A spherical wave front is that which has

Answer

None of these

Answer

A point source

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A extended source

Question 15

15. Which one of the following phenomena is not explained by Hygen’s construction of wave front?

Answer

Refraction

Answer

Reflection

Answer

Origin of spectra

Answer

Diffraction

Question 16

16. Light is a type of energy which produces sensation of

Answer

None of these

Question 17

17. Which of the following frequency ranges includes most of the electromagnetic waves emitted by the ultra – violet tubes used in a sun bed?

Answer

5 x 10⁵ to 5 x 10⁵ Hz

Answer

5 x 10⁵ to 5 x 10¹¹ Hz

Answer

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Answer

5 x 10¹¹ to 5 x 10¹⁴ Hz

Question 18

18. Which one of the following phenomena is not explained by Huygen’s construction of wave front?

Answer

Origin of spectra

Answer

Refraction

Answer

Reflection

Answer

Diffraction

Question 19

19. The locus of all points in the same phase of vibration is called:

Answer

Wavelength

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Wave number

Answer

Wave front

Question 20

20. The condition for the bright fringes formed due to constructive interference in a diffraction grating is:

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d sin θ = 2λm

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d sin θ = mλ

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md cos θ = λ

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d sin θ = m/2 λ

Question 21

21. Who devise the experimental arrangement is 1801 for studying interference effects of light?

Answer

None of these

Question 22

22. The cause of mirage observed in desert is

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Refraction

Answer

Reflection

Answer

Total internal reflection

Answer

Scattering

Question 23

23. In Newton’s rings the point of contact of the lend and the glass plate, the air film is

Answer

None of these

Question 24

24. Ray optics is valid, when characteristic dimensions are

Answer

Much smaller than the wavelength of length

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Of the same order as the wavelength of light

Answer

Much larger than the wavelength of light

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Of the order of one millimeter

Question 25

25. The condition for constructive interference of two coherent beams is that the path difference should be

Answer

Integral multiple of λ/2

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Even integral multiple of λ

Answer

Odd integral multiple of λ/2

Answer

Integral multiple of λ

Question 26

26. In the Michelson Interferometer, if m number fringes pass through a reference point when the mirror is moved a distance d, then the wavelength of the light can be found by the formula:

Answer

λ = 2π dm

Question 27

27. The splitting of white light into several colors on passing through a glass prism is due to

Answer

Interference

Answer

Diffraction

Answer

Refraction

Answer

Reflection

Question 28

28. If a source of light is moving away from stationary observer, then frequency of light wave appears to change because of

Answer

Interference

Answer

None of these

Answer

Doppler’s effect

Answer

Diffraction

Question 29

29. In a plane polarized light

Answer

Vibration take place in a direction perpendicular to the direction of propagation of light

Answer

No vibration at all

Answer

Vibration in two mutually perpendicular directions

Answer

Vibration in all direction

Question 30

30. The fringe spacing in case of blue light

Answer

None of these

Answer

Remains the same

Question 31

31. In Young’s experiment, a dark fringe is observed when:

Answer

d Sin θ = (m + 1/2)λ

Answer

2π Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Answer

½ d Sin θ = mλ

Question 32

32. Central spot of New tons rings

Answer

Bright for large wavelength

Answer

Dart for large wavelength

Question 33

33. Why laser rays are used to measure long distance?

Answer

Laser rays are most coherent waves

Answer

Laser rays propagate in a straight line

Answer

Laser rays are not absorbed

Answer

Laser rays are high velocity waves

Question 34

34. A prism splits a beam of white light into its seven constituent colors. This is so because

Answer

Energy of different colors is different

Answer

Phase of different colors is different

Answer

Velocity of different colors is different

Answer

Amplitude of different colors is different

Question 35

35. If the path difference must be half-integral number wavelength

Answer

d in θ = (m + ½ )1/λ

Answer

d sin θ = (m + 1/2)π/λ

Answer

d sin θ = (m + 1)λ

Answer

d sin θ = (m + 1/2)λ

Question 36

36. In the phenomenon of interference, the bright ad dark fringes are of

Answer

None of these

Answer

Different width

Answer

Dark fringes are thicker than bright

Answer

Equal width

Question 37

37. The relation of constructive interference in X-ray diffraction is called

Answer

Laue’s pattern

Answer

Bragg’s law

Answer

Huygen’s formula

Answer

Compton effect

Question 38

38. When the light is incident on polarizing angle which of the following is completely polarized?

Answer

Neither reflected nor refracted light

Answer

Both reflected and refracted light

Answer

Refracted light

Answer

Reflected light

Question 39

39. Two sources of light are coherent if they emit rays of

Answer

Same amplitude and wavelength

Answer

Same amplitude of vibration

Answer

Same wave length with constant phase difference

Answer

Same wavelength

Question 40

40. For constructive interference the path difference is

Answer

(m – 1)λ

Question 41

41. Longitudinal waves do not exhibit

Answer

Reflection

Answer

Polarization

Answer

Refraction

Answer

Diffraction

Question 42

42. Light appears to travel in straight lies since

Answer

Its velocity is very large

Answer

It is reflected by the atmosphere

Answer

Its wavelength is very small

Answer

It is not absorbed by the atmosphere

Question 43

43. Light on passing through a Polaroid is

Answer

Elliptically polarized

Answer

Un-polarized

Answer

Circularly polarized

Answer

Plane polarized

Question 44

44. Curtain less windows are made by making use of __________ of light.

Answer

Polarization

Answer

Transmission

Answer

Absorption

Answer

Diffraction

Question 45

45. A ____________ lens is used to form Newton’s rings.

Answer

Plano-concave

Answer

Convexo-concave

Answer

Plano-convex

Answer

Double-convex

Question 46

46. When crest of one wave falls over the trough of the other wave this phenomenon is known as

Answer

Constructive interference

Answer

Polarization

Answer

Diffraction

Answer

Destructive interference

Question 47

47. The principle of Michelson’s interferometers is

Answer

Refraction

Answer

Reflection

Answer

Interference

Answer

Dispersion

Question 48

48. The light produced by a laser is all the following except

Answer

In the form of a narrow beam

Answer

Monochromatic

Answer

Incoherent

Answer

Electromagnetic

Question 49

49. Which effect provides direct experimental evidence that light is a transverse, rather than a longitudinal, wave motion?

Answer

Light can be diffracted

Answer

Two coherent light waves can be made to interfere

Answer

The intensity of light from a point source falls off inversely as the square of the distance from the source

Answer

Light can be polarized

Question 50

50. In Huygen’s wave theory, the locus of all points in the same state of vibration is called

Answer

A half-period zone

Answer

Wave front

Question 51

51. On a rainy day, if there is an oil drop on tar road, colored rings are seen around this drop. This is because of

Answer

Total internal reflection of light

Answer

Interference pattern produced due to thin oil film

Answer

Diffraction pattern

Answer

Polarization

Question 52

52. According to Huygen, every point on a wave front may be regarded as a __________ of secondary wavelets.

Question 53

53. A diffraction grating has 500 lines per mm. Its slit spacing or grating element will be equal to

Answer

5 x 10¯³ mm

Answer

2 x 10¯³ mm

Answer

2 x 10¯⁵ mm

Question 54

54. In Young double slit experiment, if white light is used

Answer

No interference fringes will be seen

Answer

Alternate dark and bright fringes will be seen

Answer

Impossible to predict

Answer

Colored fringes will be seen

Question 55

55. Diffraction effect is

Answer

Less for a sharp edge

Answer

More for a round edge

Answer

Less for a round edge

Answer

More for a sharp edge

Question 56

56. Signal from a remote control to the device operated by it tracels with the speed of:

Answer

Supersonics

Answer

Ultrasonics

Question 57

57. Ultra – violet rays differ from X-rays in that ultra – violet rays

Answer

Do not affect a photographic plate

Answer

Cannot be diffracted

Answer

Cannot be polarized

Answer

Have a lower frequency

Question 58

58. The idea of light as wave produced by

Answer

Thomos young

Question 59

59. The locus of all points in a medium having the same phase of vibration is called

Answer

Wave front

Answer

Wavelength

Question 60

60. The contrast in the fringes in any interference pattern depends on

Answer

Wavelength

Answer

Intensity ratio of the sources

Answer

Distance between the slits

Answer

Fringe width

Question 61

61. To demonstrate the phenomenon of interference we require two sources that emit radiation

Answer

Of the same frequency and having definite phase relationship

Answer

Different wavelength

Answer

Of nearly the same frequency

Answer

Of same frequency

Question 62

62. Interference was observed in interference chamber, when air was present, now the chamber is evacuated and if the same light is used, a careful observer will see

Answer

Interference in which breadth of the fringe will be slightly increase

Answer

No interference

Answer

Interference with bright bands

Answer

Interference with dark bands

Question 63

63. If the dark fringe is to be observed then we have relation

Answer

Y = (m + 1) λL/d

Answer

Y = (m + 1/2) λd/L

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + ½) dL/λ

Question 64

64. In an interference pattern

Answer

Dark fringes are wider than bright fringe

Answer

Both dark and bright fringes are of equal width

Answer

Central fringes are brighter than the outer fringes

Answer

Bright fringes are wider than dark fringes

Answer 210

Interference

Answer 211

Photoelectric effect

Answer 212

Diffraction

Answer 213

Polarization

Answer 214

Comparable

Answer 215

Not comparable

Answer 216

None of these

Answer 217

Interference

Answer 218

Diffraction

Answer 219

Polarization

Answer 220

Photoelectric effect

Answer 221

Ultraviolet rays

Answer 222

Sound waves

Answer 223

Radio waves

Answer 224

Opposite to each other

Answer 225

At a far off distance

Answer 226

Coinciding

Answer 227

Close together

Answer 228

Total internal reflection of light

Answer 229

Polarization

Answer 230

Interference pattern produced due to thin oil film

Answer 231

Diffraction pattern

Answer 232

It is constant at the center

Answer 233

Increasing gradually

Answer 234

None of these

Answer 235

Decreasing gradually

Answer 236

Polarization

Answer 237

Diffraction

Answer 238

Interference

Answer 239

Dispersion

Answer 240

Interferometer

Answer 241

Diffraction grating

Answer 242

Convex lens

Answer 243

A transverse waves

Answer 244

A longitudinal wave

Answer 245

A sound wave

Answer 246

An electromagnetic wave

Answer 247

Polarization

Answer 248

Interference

Answer 249

Diffraction

Answer 250

Reflection

Answer 251

Reflection

Answer 252

Polarization

Answer 253

Scattering

Answer 254

Diffraction

Answer 255

The intensity of light from a point source falls off inversely as the square of the distance from the source

Answer 256

Light can be polarized

Answer 257

Light can be diffracted

Answer 258

Two coherent light waves can be made to interfere

Answer 259

All of these

Answer 260

Wavelength

Answer 261

Band emission spectrum

Answer 262

Line absorption spectrum

Answer 263

Band absorption spectrum

Answer 264

Line emission spectrum

Answer 265

Of same amplitude

Answer 266

Have constant phase difference

Answer 267

Be close to each other

Answer 268

Rays are not normal to wave front

Answer 269

Rays may be normal to wave front

Answer 270

There is no relationship between rays and wave fronts

Answer 271

Rays are normal to wave front

Answer 272

Produce unpolarised light

Answer 273

Increase intensity of light

Answer 274

Produce polarized light

Answer 275

Reduced intensity of light

Answer 276

Using monochromatic light of longer wavelength

Answer 277

Using monochromatic light of higher frequency

Answer 278

Decreasing the distance between the screen and the slits

Answer 279

Increasing the distance between the slits

Answer 280

3 x 10⁸ ms¯¹

Answer 281

3 x 10⁵ ms¯¹

Answer 282

3 x 10¯¹⁰ ms¯¹

Answer 283

3.1 x 10⁸ ms¯¹

Answer 284

Source of secondary wave front

Answer 285

Source of wave front

Answer 286

None of these

Answer 287

A plane wave front

Answer 288

An elliptical wave front

Answer 289

A spherical wave front

Answer 290

A cylindrical wave front

Total Questions:	88
Time Allowed:	40 Minutes
Total Marks:	88
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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Physics Lights and Optics Online Mcqs Test

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Important Lights and Optics Question and Answer

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