Physics Lights and Optics Online Mcqs Test

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Question 1

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

Answer

None of these

Answer

Diffraction of light

Answer

Reflection of light

Answer

Interference of light

Question 2

2. Wavelength of light of frequency 100 Hz is

Answer

5 x 10⁶ m

Answer

4 x 10⁶ m

Answer

2 x 10⁶ m

Answer

3 x 10⁶ m

Question 3

3. 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 4

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

Answer

Reflection

Answer

Diffraction

Answer

Origin of spectra

Answer

Refraction

Question 5

5. 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 6

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

Answer

None of these

Question 7

7. In an interference pattern

Answer

Dark fringes are wider than bright fringe

Answer

Bright fringes are wider than dark fringes

Answer

Central fringes are brighter than the outer fringes

Answer

Both dark and bright fringes are of equal width

Question 8

8. 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 9

9. Choose the correct statement

Answer

Rays are not normal to wave front

Answer

There is no relationship between rays and wave fronts

Answer

Rays may be normal to wave front

Answer

Rays are normal to wave front

Question 10

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

Question 11

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

Answer

Two coherent light waves can be made to interfere

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

Question 12

12. 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 13

13. Wave front is the locus of all points in vibration are in the same

Answer

Wavelength

Answer

All of these

Question 14

14. 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

Diffraction pattern

Answer

Interference pattern produced due to thin oil film

Answer

Total internal reflection of light

Answer

Polarization

Question 15

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

Answer

An elliptical wave front

Answer

A spherical wave front

Answer

A plane wave front

Answer

A cylindrical wave front

Question 16

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

Question 17

17. The idea of light as wave produced by

Answer

Thomos young

Question 18

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

Answer

Emission spectrum

Answer

Continuous emission spectrum

Answer

Line spectrum

Answer

All of these

Question 19

19. Longitudinal waves do not exhibit

Answer

Refraction

Answer

Reflection

Answer

Polarization

Answer

Diffraction

Question 20

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

Answer

Amplitude of different colors is different

Answer

Energy of different colors is different

Answer

Velocity of different colors is different

Answer

Phase of different colors is different

Question 21

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

Answer

Wavelength

Answer

Wave number

Answer

Wave front

Question 22

22. 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 23

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

Answer

Not comparable

Answer

None of these

Answer

Comparable

Question 24

24. The principle of Michelson’s interferometers is

Answer

Reflection

Answer

Interference

Answer

Refraction

Answer

Dispersion

Question 25

25. The blue colour of the sky is due to

Answer

Reflection

Answer

Scattering

Answer

Polarization

Answer

Diffraction

Question 26

26. Huygen’s wave theory of light cannot explain

Answer

Polarization

Answer

Photoelectric effect

Answer

Interference

Answer

Diffraction

Question 27

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

Answer

Fringe width

Answer

Distance between the slits

Answer

Wavelength

Answer

Intensity ratio of the sources

Question 28

28. Diffraction effect is

Answer

More for a round edge

Answer

More for a sharp edge

Answer

Less for a sharp edge

Answer

Less for a round edge

Question 29

29. The fringe spacing in case of blue light

Answer

None of these

Answer

Remains the same

Question 30

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

Answer

A transverse waves

Answer

A sound wave

Answer

A longitudinal wave

Answer

An electromagnetic wave

Question 31

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

Answer

d sin θ = mλ

Answer

d sin θ = 2λm

Answer

md cos θ = λ

Answer

d sin θ = m/2 λ

Question 32

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

Answer

Transmission

Answer

Refraction

Answer

Diffraction

Answer

Reflection

Question 33

33. Ray optics is valid, when characteristic dimensions are

Answer

Of the same order as the wavelength of light

Answer

Of the order of one millimeter

Answer

Much smaller than the wavelength of length

Answer

Much larger than the wavelength of light

Question 34

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

Answer

Both reflected and refracted light

Answer

Neither reflected nor refracted light

Answer

Refracted light

Answer

Reflected light

Question 35

35. 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

Polarization

Answer

Diffraction pattern

Answer

Total internal reflection of light

Answer

Interference pattern produced due to thin oil film

Question 36

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

Answer

Light can be polarized

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

Question 37

37. 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 38

38. Which of the following has least wavelength?

Answer

Ultra-violet rays

Answer

Cosmic-rays

Question 39

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

Question 40

40. For the sustained interference of light, the necessary condition is that the two sources should

Answer

Have constant phase difference

Answer

Be close to each other

Answer

Of same amplitude

Question 41

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

Answer

None of these

Question 42

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

Answer

Impossible to predict

Answer

Alternate dark and bright fringes will be seen

Answer

Colored fringes will be seen

Answer

No interference fringes will be seen

Question 43

43. 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

Increasing the distance between the slits

Answer

Using monochromatic light of longer wavelength

Answer

Decreasing the distance between the screen and the slits

Question 44

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

Answer

Coinciding

Answer

Opposite to each other

Answer

Close together

Answer

At a far off distance

Question 45

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

Answer

Different wavelength

Answer

Of the same frequency and having definite phase relationship

Answer

Of nearly the same frequency

Answer

Of same frequency

Question 46

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

Answer

Laser rays are high velocity waves

Answer

Laser rays are most coherent waves

Answer

Laser rays propagate in a straight line

Answer

Laser rays are not absorbed

Question 47

47. Can two head lights of car can produce interference

Answer

None of these

Answer

Partly produce interference

Question 48

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

Answer

Convexo-concave

Answer

Plano-concave

Answer

Plano-convex

Answer

Double-convex

Question 49

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

Answer

Cannot be diffracted

Answer

Have a lower frequency

Answer

Cannot be polarized

Answer

Do not affect a photographic plate

Question 50

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

Answer

Band absorption spectrum

Answer

Band emission spectrum

Answer

Line absorption spectrum

Answer

Line emission spectrum

Question 51

51. Central spot of New tons rings

Answer

Bright for large wavelength

Answer

Dart for large wavelength

Question 52

52. The cause of mirage observed in desert is

Answer

Reflection

Answer

Refraction

Answer

Total internal reflection

Answer

Scattering

Question 53

53. A polarizer is used to

Answer

Increase intensity of light

Answer

Reduced intensity of light

Answer

Produce unpolarised light

Answer

Produce polarized light

Question 54

54. Light appears to travel in straight lies since

Answer

It is reflected by the atmosphere

Answer

Its velocity is very large

Answer

It is not absorbed by the atmosphere

Answer

Its wavelength is very small

Question 55

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

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + ½) dL/λ

Answer

Y = (m + 1/2) λd/L

Answer

Y = (m + 1) λL/d

Question 56

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

Answer

Refraction

Answer

Diffraction

Answer

Reflection

Answer

Interference

Question 57

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

Answer

d sin θ = (m + 1/2)λ

Answer

d in θ = (m + ½ )1/λ

Answer

d sin θ = (m + 1)λ

Answer

d sin θ = (m + 1/2)π/λ

Question 58

58. Light on passing through a Polaroid is

Answer

Un-polarized

Answer

Plane polarized

Answer

Circularly polarized

Answer

Elliptically polarized

Question 59

59. Huygen’s wave theory of light cannot explain

Answer

Diffraction

Answer

Interference

Answer

Photoelectric effect

Answer

Polarization

Question 60

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

Answer

Same wavelength

Answer

Same wave length with constant phase difference

Answer

Same amplitude and wavelength

Answer

Same amplitude of vibration

Question 61

61. For constructive interference the path difference is

Answer

(m – 1)λ

Question 62

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

Answer

d Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Answer

2π Sin θ = (m + 1/2)λ

Answer

½ d Sin θ = mλ

Question 63

63. According to the electromagnetic theory, the speed of light is approximately:

Answer

3 x 10¯¹⁰ ms¯¹

Answer

3.1 x 10⁸ ms¯¹

Answer

3 x 10⁵ ms¯¹

Answer

3 x 10⁸ ms¯¹

Question 64

64. 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

No interference

Answer

Interference with bright bands

Answer

Interference in which breadth of the fringe will be slightly increase

Answer

Interference with dark bands

Answer 211

Source of wave front

Answer 212

None of these

Answer 213

Source of secondary wave front

Answer 214

Supersonics

Answer 215

Ultrasonics

Answer 216

5 x 10¹¹ to 5 x 10¹⁴ Hz

Answer 217

5 x 10⁵ to 5 x 10⁵ Hz

Answer 218

5 x 10⁵ to 5 x 10¹¹ Hz

Answer 219

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Answer 220

Laue’s pattern

Answer 221

Bragg’s law

Answer 222

Compton effect

Answer 223

Huygen’s formula

Answer 224

None of these

Answer 225

Origin of spectra

Answer 226

Refraction

Answer 227

Reflection

Answer 228

Diffraction

Answer 229

None of these

Answer 230

Increasing gradually

Answer 231

It is constant at the center

Answer 232

Decreasing gradually

Answer 233

Destructive interference

Answer 234

Polarization

Answer 235

Constructive interference

Answer 236

Diffraction

Answer 237

None of these

Answer 238

A extended source

Answer 239

A point source

Answer 240

Incoherent

Answer 241

Monochromatic

Answer 242

In the form of a narrow beam

Answer 243

Electromagnetic

Answer 244

Wave front

Answer 245

Wavelength

Answer 246

Dark fringes are thicker than bright

Answer 247

Different width

Answer 248

Equal width

Answer 249

None of these

Answer 250

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

Answer 251

Vibration in two mutually perpendicular directions

Answer 252

No vibration at all

Answer 253

Vibration in all direction

Answer 254

Transmission

Answer 255

Diffraction

Answer 256

Polarization

Answer 257

Absorption

Answer 258

Reflection

Answer 259

Polarization

Answer 260

Interference

Answer 261

Diffraction

Answer 262

Distance between them increases

Answer 263

They are adjacent with no space in between

Answer 264

Distance between then decreases

Answer 265

Equally spaced

Answer 266

Even integral multiple of λ

Answer 267

Integral multiple of λ/2

Answer 268

Integral multiple of λ

Answer 269

Odd integral multiple of λ/2

Answer 270

Diffraction

Answer 271

Interference

Answer 272

Doppler’s effect

Answer 273

None of these

Answer 274

Interferometer

Answer 275

Convex lens

Answer 276

Diffraction grating

Answer 277

Ultraviolet rays

Answer 278

Sound waves

Answer 279

Radio waves

Answer 280

Speed of propagation greater than wave

Answer 281

Speed of propagation less than the wave

Answer 282

Speed of propagation of the wave

Answer 283

Mechanical waves

Answer 284

Transverse

Answer 285

Longitudinal

Answer 286

Matter waves

Answer 287

Dispersion

Answer 288

Diffraction

Answer 289

Polarization

Answer 290

Interference

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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