Physics Lights and Optics Online Mcqs Test

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Question 1

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

Answer

Laser rays propagate in a straight line

Answer

Laser rays are not absorbed

Answer

Laser rays are high velocity waves

Answer

Laser rays are most coherent waves

Question 2

2. For constructive interference the path difference is

Answer

(m – 1)λ

Question 3

3. Appearance of colour in thin films is due to

Answer

Interference

Answer

Polarization

Answer

Diffraction

Answer

Dispersion

Question 4

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

Answer

A plane wave front

Answer

A spherical wave front

Answer

A cylindrical wave front

Answer

An elliptical wave front

Question 5

5. Diffraction fringes are

Answer

Distance between then decreases

Answer

Equally spaced

Answer

They are adjacent with no space in between

Answer

Distance between them increases

Question 6

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

Answer

Bragg’s law

Answer

Laue’s pattern

Answer

Huygen’s formula

Answer

Compton effect

Question 7

7. 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 polarized

Answer

Light can be diffracted

Question 8

8. Can two head lights of car can produce interference

Answer

Partly produce interference

Answer

None of these

Question 9

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

Answer

d sin θ = 2λm

Answer

md cos θ = λ

Answer

d sin θ = m/2 λ

Answer

d sin θ = mλ

Question 10

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

Answer

Even integral multiple of λ

Answer

Integral multiple of λ/2

Answer

Odd integral multiple of λ/2

Answer

Integral multiple of λ

Question 11

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

Answer

½ d Sin θ = mλ

Answer

2π Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Answer

d Sin θ = (m + 1/2)λ

Question 12

12. 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

Interference pattern produced due to thin oil film

Answer

Total internal reflection of light

Answer

Diffraction pattern

Question 13

13. Central spot of New tons rings

Answer

Bright for large wavelength

Answer

Dart for large wavelength

Question 14

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

Answer

A longitudinal wave

Answer

A transverse waves

Answer

An electromagnetic wave

Answer

A sound wave

Question 15

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

Answer

None of these

Question 16

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

Answer

3 x 10¯¹⁰ ms¯¹

Answer

3 x 10⁵ ms¯¹

Answer

3.1 x 10⁸ ms¯¹

Answer

3 x 10⁸ ms¯¹

Question 17

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

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

Answer

Be close to each other

Answer

Have constant phase difference

Answer

Of same amplitude

Question 20

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

Answer

Reflection of light

Answer

None of these

Answer

Interference of light

Answer

Diffraction of light

Question 21

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

Answer

Double-convex

Answer

Plano-convex

Answer

Convexo-concave

Answer

Plano-concave

Question 22

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

Answer

Wavelength

Answer

Wave number

Answer

Wave front

Question 23

23. The cause of mirage observed in desert is

Answer

Total internal reflection

Answer

Scattering

Answer

Reflection

Answer

Refraction

Question 24

24. 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 dark bands

Answer

Interference with bright bands

Answer

Interference in which breadth of the fringe will be slightly increase

Answer

No interference

Question 25

25. The principle of Michelson’s interferometers is

Answer

Interference

Answer

Refraction

Answer

Reflection

Answer

Dispersion

Question 26

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

Answer

d sin θ = (m + 1)λ

Answer

d in θ = (m + ½ )1/λ

Answer

d sin θ = (m + 1/2)λ

Answer

d sin θ = (m + 1/2)π/λ

Question 27

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

Answer

Incoherent

Answer

Monochromatic

Answer

In the form of a narrow beam

Answer

Electromagnetic

Question 28

28. Ray optics is valid, when characteristic dimensions are

Answer

Of the same order as the wavelength of light

Answer

Much larger than the wavelength of light

Answer

Of the order of one millimeter

Answer

Much smaller than the wavelength of length

Question 29

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

Answer

Absorption

Answer

Transmission

Answer

Diffraction

Answer

Polarization

Question 30

30. 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

Polarization

Answer

Total internal reflection of light

Answer

Interference pattern produced due to thin oil film

Question 31

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

Answer

None of these

Question 32

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

Answer

Wave front

Answer

Wavelength

Question 33

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

Question 34

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

Answer

Supersonics

Answer

Ultrasonics

Question 35

35. A spherical wave front is that which has

Answer

None of these

Answer

A point source

Answer

A extended source

Question 36

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

Answer

Distance between the slits

Answer

Fringe width

Answer

Wavelength

Answer

Intensity ratio of the sources

Question 37

37. Which one of the following cannot be polarized?

Answer

Sound waves

Answer

Radio waves

Answer

Ultraviolet rays

Question 38

38. Huygen’s wave theory of light cannot explain

Answer

Interference

Answer

Photoelectric effect

Answer

Diffraction

Answer

Polarization

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. 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 41

41. In an interference pattern

Answer

Central fringes are brighter than the outer fringes

Answer

Both dark and bright fringes are of equal width

Answer

Bright fringes are wider than dark fringes

Answer

Dark fringes are wider than bright fringe

Question 42

42. Which of the following properties show light is transverse wave in nature?

Answer

Interference

Answer

Diffraction

Answer

Polarization

Answer

Reflection

Question 43

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

Answer

Wave front

Answer

A half-period zone

Question 44

44. The fringe spacing in case of blue light

Answer

Remains the same

Answer

None of these

Question 45

45. Light on passing through a Polaroid is

Answer

Un-polarized

Answer

Plane polarized

Answer

Circularly polarized

Answer

Elliptically polarized

Question 46

46. Crystals of a material can behave as

Answer

Diffraction grating

Answer

Interferometer

Answer

Convex lens

Question 47

47. In a plane polarized light

Answer

Vibration in two mutually perpendicular directions

Answer

No vibration at all

Answer

Vibration in all direction

Answer

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

Question 48

48. Which of the following has least wavelength?

Answer

Cosmic-rays

Answer

Ultra-violet rays

Question 49

49. Polarization occurs only in ________ waves

Answer

Longitudinal

Answer

Matter waves

Answer

Mechanical waves

Answer

Transverse

Question 50

50. In Michelson interferometer to switch the fringe from bright to dark the mirror should be displaced through

Question 51

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

Answer

Cannot be diffracted

Answer

Cannot be polarized

Answer

Have a lower frequency

Answer

Do not affect a photographic plate

Question 52

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

Answer

Monochromatic

Answer

Electromagnetic

Answer

In the form of a narrow beam

Answer

Incoherent

Question 53

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

Answer

Y = (m + ½) dL/λ

Answer

Y = (m + 1) λL/d

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + 1/2) λd/L

Question 54

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

Answer

2 x 10¯³ mm

Answer

2 x 10¯⁵ mm

Answer

5 x 10¯³ mm

Question 55

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

Question 56

56. 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 10¹¹ to 5 x 10¹⁴ Hz

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

Question 57

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

Answer

Refracted light

Answer

Neither reflected nor refracted light

Answer

Reflected light

Answer

Both reflected and refracted light

Question 58

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

Answer

Same wavelength

Answer

Same amplitude of vibration

Answer

Same amplitude and wavelength

Answer

Same wave length with constant phase difference

Question 59

59. 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 60

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

Answer

Wavelength

Answer

All of these

Question 61

61. Diffraction effect is

Answer

More for a round edge

Answer

Less for a sharp edge

Answer

More for a sharp edge

Answer

Less for a round edge

Question 62

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

Answer

Opposite to each other

Answer

At a far off distance

Answer

Coinciding

Answer

Close together

Question 63

63. Huygen’s wave theory of light cannot explain

Answer

Interference

Answer

Diffraction

Answer

Photoelectric effect

Answer

Polarization

Question 64

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

Answer

No interference fringes will be seen

Answer

Impossible to predict

Answer

Alternate dark and bright fringes will be seen

Answer

Colored fringes will be seen

Answer 210

Scattering

Answer 211

Polarization

Answer 212

Diffraction

Answer 213

Reflection

Answer 214

Increasing the distance between the slits

Answer 215

Using monochromatic light of longer wavelength

Answer 216

Decreasing the distance between the screen and the slits

Answer 217

Using monochromatic light of higher frequency

Answer 218

Produce unpolarised light

Answer 219

Produce polarized light

Answer 220

Reduced intensity of light

Answer 221

Increase intensity of light

Answer 222

Energy of different colors is different

Answer 223

Velocity of different colors is different

Answer 224

Phase of different colors is different

Answer 225

Amplitude of different colors is different

Answer 226

Elliptical

Answer 227

None of these

Answer 228

Rays may be normal to wave front

Answer 229

Rays are not normal to wave front

Answer 230

There is no relationship between rays and wave fronts

Answer 231

Rays are normal to wave front

Answer 232

Reflection

Answer 233

Origin of spectra

Answer 234

Diffraction

Answer 235

Refraction

Answer 236

Thomos young

Answer 237

Refraction

Answer 238

Interference

Answer 239

Diffraction

Answer 240

Reflection

Answer 241

None of these

Answer 242

Source of secondary wave front

Answer 243

Source of wave front

Answer 244

Polarization

Answer 245

Destructive interference

Answer 246

Diffraction

Answer 247

Constructive interference

Answer 248

None of these

Answer 249

Diffraction

Answer 250

Interference

Answer 251

Doppler’s effect

Answer 252

Dark fringes are thicker than bright

Answer 253

None of these

Answer 254

Equal width

Answer 255

Different width

Answer 256

None of these

Answer 257

Increasing gradually

Answer 258

Decreasing gradually

Answer 259

It is constant at the center

Answer 260

Diffraction

Answer 261

Refraction

Answer 262

Reflection

Answer 263

Transmission

Answer 264

Band emission spectrum

Answer 265

Band absorption spectrum

Answer 266

Line absorption spectrum

Answer 267

Line emission spectrum

Answer 268

λ = 2π dm

Answer 269

None of these

Answer 270

A Plano convex lens and simple glass sheet

Answer 271

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

Answer 272

A Plano convex lens and the plane glass plate

Answer 273

Its wavelength is very small

Answer 274

Its velocity is very large

Answer 275

It is reflected by the atmosphere

Answer 276

It is not absorbed by the atmosphere

Answer 277

Speed of propagation of the wave

Answer 278

Speed of propagation greater than wave

Answer 279

Speed of propagation less than the wave

Answer 280

Diffraction

Answer 281

Reflection

Answer 282

Polarization

Answer 283

Refraction

Answer 284

Different wavelength

Answer 285

Of the same frequency and having definite phase relationship

Answer 286

Of same frequency

Answer 287

Of nearly the same frequency

Answer 288

Not comparable

Answer 289

Comparable

Answer 290

None of these

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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