Physics Lights and Optics Online Mcqs Test

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Question 1

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

Answer

Diffraction

Answer

Reflection

Answer

Origin of spectra

Answer

Refraction

Question 2

2. Appearance of colour in thin films is due to

Answer

Dispersion

Answer

Interference

Answer

Polarization

Answer

Diffraction

Question 3

3. Choose the correct statement

Answer

Rays are normal to wave front

Answer

Rays may be normal to wave front

Answer

There is no relationship between rays and wave fronts

Answer

Rays are not normal to wave front

Question 4

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

Answer

Same amplitude and wavelength

Answer

Same wave length with constant phase difference

Answer

Same wavelength

Answer

Same amplitude of vibration

Question 5

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

Answer

Interference

Answer

Diffraction

Answer

Doppler’s effect

Answer

None of these

Question 6

6. 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 with bright bands

Answer

Interference with dark bands

Answer

No interference

Answer

Interference in which breadth of the fringe will be slightly increase

Question 7

7. 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

Interference pattern produced due to thin oil film

Answer

Diffraction pattern

Answer

Total internal reflection of light

Answer

Polarization

Question 8

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

Answer

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

Answer

Two coherent light waves can be made to interfere

Answer

Light can be diffracted

Answer

Light can be polarized

Question 9

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

Answer

None of these

Question 10

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

Answer

Fringe width

Answer

Wavelength

Answer

Distance between the slits

Answer

Intensity ratio of the sources

Question 11

11. 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 12

12. Wavelength of light of frequency 100 Hz is

Answer

4 x 10⁶ m

Answer

2 x 10⁶ m

Answer

5 x 10⁶ m

Answer

3 x 10⁶ m

Question 13

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

Answer

d sin θ = mλ

Answer

md cos θ = λ

Answer

d sin θ = 2λm

Answer

d sin θ = m/2 λ

Question 14

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

Answer

Wave front

Answer

Wave number

Answer

Wavelength

Question 15

15. One condition for interference is that the two sources should be coherent and:

Answer

Opposite to each other

Answer

Coinciding

Answer

Close together

Answer

At a far off distance

Question 16

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

Answer

Supersonics

Answer

Ultrasonics

Question 17

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

Answer

Double-convex

Answer

Plano-convex

Answer

Convexo-concave

Answer

Plano-concave

Question 18

18. 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 10¹⁴ to 5 x 10¹⁷ Hz

Answer

5 x 10¹¹ to 5 x 10¹⁴ Hz

Answer

5 x 10⁵ to 5 x 10⁵ Hz

Answer

5 x 10⁵ to 5 x 10¹¹ Hz

Question 19

19. Which one of the following cannot be polarized?

Answer

Radio waves

Answer

Ultraviolet rays

Answer

Sound waves

Question 20

20. Can two head lights of car can produce interference

Answer

Partly produce interference

Answer

None of these

Question 21

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

Answer

Diffraction

Answer

Origin of spectra

Answer

Refraction

Answer

Reflection

Question 22

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

Answer

Diffraction

Answer

Reflection

Answer

Transmission

Answer

Refraction

Question 23

23. 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 same frequency

Answer

Of nearly the same frequency

Question 24

24. 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 25

25. The fringe spacing in case of blue light

Answer

None of these

Answer

Remains the same

Question 26

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

Answer

Monochromatic

Answer

Incoherent

Answer

In the form of a narrow beam

Answer

Electromagnetic

Question 27

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

Answer

Colored fringes will be seen

Answer

No interference fringes will be seen

Answer

Impossible to predict

Answer

Alternate dark and bright fringes will be seen

Question 28

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

Answer

In the form of a narrow beam

Answer

Incoherent

Answer

Electromagnetic

Answer

Monochromatic

Question 29

29. Due to Plano convex lens and the plane glass plate the thickness of air film changes from the center to outward

Answer

Decreasing gradually

Answer

It is constant at the center

Answer

Increasing gradually

Answer

None of these

Question 30

30. Coherent monochromatic light illuminates two narrow parallel slits and the interference pattern that results is observed on a screen some distance beyond the slits. Which modification increases the separation between the dark lines of the interference pattern?

Answer

Using monochromatic light of higher frequency

Answer

Decreasing the distance between the screen and the slits

Answer

Increasing the distance between the slits

Answer

Using monochromatic light of longer wavelength

Question 31

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

Answer

Cannot be diffracted

Answer

Do not affect a photographic plate

Answer

Cannot be polarized

Answer

Have a lower frequency

Question 32

32. Fraunhoffer’s lines commonly visible in the sun’s spectrum are examples of

Answer

Line absorption spectrum

Answer

Line emission spectrum

Answer

Band absorption spectrum

Answer

Band emission spectrum

Question 33

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

Answer

Diffraction

Answer

Absorption

Answer

Polarization

Answer

Transmission

Question 34

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

Answer

Diffraction of light

Answer

Reflection of light

Answer

Interference of light

Answer

None of these

Question 35

35. Central spot of New tons rings

Answer

Bright for large wavelength

Answer

Dart for large wavelength

Question 36

36. Huygen’s wave theory of light cannot explain

Answer

Diffraction

Answer

Photoelectric effect

Answer

Polarization

Answer

Interference

Question 37

37. Every point of a wave front may be considered as a

Answer

None of these

Answer

Source of secondary wave front

Answer

Source of wave front

Question 38

38. Crystals of a material can behave as

Answer

Convex lens

Answer

Diffraction grating

Answer

Interferometer

Question 39

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

Answer

Light can be polarized

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 diffracted

Answer

Two coherent light waves can be made to interfere

Question 40

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

Answer

d sin θ = (m + 1/2)π/λ

Answer

d sin θ = (m + 1/2)λ

Answer

d in θ = (m + ½ )1/λ

Answer

d sin θ = (m + 1)λ

Question 41

41. The setting of Newton’s rings is

Answer

A Plano convex lens and the plane glass plate

Answer

A Plano convex lens and simple glass sheet

Answer

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

Answer

None of these

Question 42

42. Huygen’s wave theory of light cannot explain

Answer

Photoelectric effect

Answer

Diffraction

Answer

Interference

Answer

Polarization

Question 43

43. A spherical wave front is that which has

Answer

None of these

Answer

A extended source

Answer

A point source

Question 44

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

Answer

Both reflected and refracted light

Answer

Reflected light

Answer

Refracted light

Answer

Neither reflected nor refracted light

Question 45

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

Answer

Reflection

Answer

Refraction

Answer

Diffraction

Answer

Interference

Question 46

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

Answer

Line spectrum

Answer

Emission spectrum

Answer

All of these

Answer

Continuous emission spectrum

Question 47

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

Answer

None of these

Question 48

48. Longitudinal waves do not exhibit

Answer

Reflection

Answer

Polarization

Answer

Refraction

Answer

Diffraction

Question 49

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

Answer

Integral multiple of λ/2

Answer

Odd integral multiple of λ/2

Answer

Integral multiple of λ

Answer

Even integral multiple of λ

Question 50

50. If a wave can be polarized, it must be

Answer

A transverse waves

Answer

An electromagnetic wave

Answer

A sound wave

Answer

A longitudinal wave

Question 51

51. Intensities of the two waves of light are l and 4l. The maximum intensity of the resultant wave after superposition is

Question 52

52. Polarization occurs only in ________ waves

Answer

Transverse

Answer

Longitudinal

Answer

Matter waves

Answer

Mechanical waves

Question 53

53. Light on passing through a Polaroid is

Answer

Elliptically polarized

Answer

Plane polarized

Answer

Circularly polarized

Answer

Un-polarized

Question 54

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

Answer

Wavelength

Answer

Wave front

Question 55

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

Answer

Phase of different colors is different

Answer

Velocity of different colors is different

Answer

Energy of different colors is different

Answer

Amplitude of different colors is different

Question 56

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

Answer

Y = (m + 1) λL/d

Answer

Y = (m + ½) dL/λ

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + 1/2) λd/L

Question 57

57. 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 58

58. Which of the following has least wavelength?

Answer

Cosmic-rays

Answer

Ultra-violet rays

Question 59

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

Answer

Constructive interference

Answer

Diffraction

Answer

Destructive interference

Answer

Polarization

Question 60

60. A thin film is a transparent medium whose thickness with the wavelength of light are

Answer

None of these

Answer

Not comparable

Answer

Comparable

Question 61

61. A point source of light placed in a homogeneous medium gives rise to

Answer

A plane wave front

Answer

A cylindrical wave front

Answer

A spherical wave front

Answer

An elliptical wave front

Question 62

62. The idea of light as wave produced by

Answer

Thomos young

Question 63

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

Answer

2π Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Answer

d Sin θ = (m + 1/2)λ

Answer

½ d Sin θ = mλ

Question 64

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

Answer

Laser rays propagate in a straight line

Answer

Laser rays are most coherent waves

Answer

Laser rays are not absorbed

Answer

Laser rays are high velocity waves

Answer 219

Wave front

Answer 220

A half-period zone

Answer 221

Refraction

Answer 222

Reflection

Answer 223

Interference

Answer 224

Dispersion

Answer 225

3 x 10⁸ ms¯¹

Answer 226

3 x 10¯¹⁰ ms¯¹

Answer 227

3.1 x 10⁸ ms¯¹

Answer 228

3 x 10⁵ ms¯¹

Answer 229

Of same amplitude

Answer 230

Be close to each other

Answer 231

Have constant phase difference

Answer 232

Both dark and bright fringes are of equal width

Answer 233

Dark fringes are wider than bright fringe

Answer 234

Central fringes are brighter than the outer fringes

Answer 235

Bright fringes are wider than dark fringes

Answer 236

(m – 1)λ

Answer 237

None of these

Answer 238

Produce polarized light

Answer 239

Increase intensity of light

Answer 240

Reduced intensity of light

Answer 241

Produce unpolarised light

Answer 242

Huygen’s formula

Answer 243

Laue’s pattern

Answer 244

Compton effect

Answer 245

Bragg’s law

Answer 246

Speed of propagation greater than wave

Answer 247

Speed of propagation less than the wave

Answer 248

Speed of propagation of the wave

Answer 249

All of these

Answer 250

Wavelength

Answer 251

Much larger than the wavelength of light

Answer 252

Much smaller than the wavelength of length

Answer 253

Of the same order as the wavelength of light

Answer 254

Of the order of one millimeter

Answer 255

Interference pattern produced due to thin oil film

Answer 256

Total internal reflection of light

Answer 257

Diffraction pattern

Answer 258

Polarization

Answer 259

No vibration at all

Answer 260

Vibration in two mutually perpendicular directions

Answer 261

Vibration in all direction

Answer 262

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

Answer 263

Less for a sharp edge

Answer 264

Less for a round edge

Answer 265

More for a sharp edge

Answer 266

More for a round edge

Answer 267

Refraction

Answer 268

Reflection

Answer 269

Scattering

Answer 270

Total internal reflection

Answer 271

Equal width

Answer 272

Different width

Answer 273

Dark fringes are thicker than bright

Answer 274

None of these

Answer 275

They are adjacent with no space in between

Answer 276

Distance between then decreases

Answer 277

Equally spaced

Answer 278

Distance between them increases

Answer 279

Polarization

Answer 280

Reflection

Answer 281

Scattering

Answer 282

Diffraction

Answer 283

Its wavelength is very small

Answer 284

It is not absorbed by the atmosphere

Answer 285

It is reflected by the atmosphere

Answer 286

Its velocity is very large

Answer 287

Polarization

Answer 288

Diffraction

Answer 289

Interference

Answer 290

Reflection

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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