Physics Lights and Optics Online Mcqs Test

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Question 1

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

Answer

Refraction

Answer

Interference

Answer

Diffraction

Answer

Reflection

Question 2

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

Answer

None of these

Question 3

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

Answer

Supersonics

Answer

Ultrasonics

Question 4

4. The cause of mirage observed in desert is

Answer

Refraction

Answer

Reflection

Answer

Scattering

Answer

Total internal reflection

Question 5

5. Huygen’s wave theory of light cannot explain

Answer

Interference

Answer

Photoelectric effect

Answer

Diffraction

Answer

Polarization

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 dark bands

Answer

Interference with bright bands

Answer

Interference in which breadth of the fringe will be slightly increase

Answer

No interference

Question 7

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

Answer

None of these

Question 8

8. 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 9

9. A spherical wave front is that which has

Answer

None of these

Answer

A extended source

Answer

A point source

Question 10

10. The idea of light as wave produced by

Answer

Thomos young

Question 11

11. 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 high velocity waves

Answer

Laser rays are not absorbed

Question 12

12. Appearance of colour in thin films is due to

Answer

Diffraction

Answer

Polarization

Answer

Interference

Answer

Dispersion

Question 13

13. The blue colour of the sky is due to

Answer

Reflection

Answer

Diffraction

Answer

Scattering

Answer

Polarization

Question 14

14. Light on passing through a Polaroid is

Answer

Elliptically polarized

Answer

Un-polarized

Answer

Plane polarized

Answer

Circularly polarized

Question 15

15. 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 16

16. Longitudinal waves do not exhibit

Answer

Refraction

Answer

Polarization

Answer

Reflection

Answer

Diffraction

Question 17

17. In an interference pattern

Answer

Central fringes are brighter than the outer fringes

Answer

Bright fringes are wider than dark fringes

Answer

Both dark and bright fringes are of equal width

Answer

Dark fringes are wider than bright fringe

Question 18

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

Answer

Incoherent

Answer

In the form of a narrow beam

Answer

Monochromatic

Answer

Electromagnetic

Question 19

19. 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 20

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

Answer

Speed of propagation of the wave

Answer

Speed of propagation less than the wave

Answer

Speed of propagation greater than wave

Question 21

21. Polarization occurs only in ________ waves

Answer

Longitudinal

Answer

Mechanical waves

Answer

Matter waves

Answer

Transverse

Question 22

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

Answer

Source of wave front

Answer

Source of secondary wave front

Answer

None of these

Question 23

23. The setting of Newton’s rings is

Answer

A Plano convex lens and the plane glass plate

Answer

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

Answer

A Plano convex lens and simple glass sheet

Answer

None of these

Question 24

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

Answer

md cos θ = λ

Answer

d sin θ = 2λm

Answer

d sin θ = mλ

Answer

d sin θ = m/2 λ

Question 25

25. 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 + 1/2)π/λ

Answer

d sin θ = (m + 1)λ

Question 26

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

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + 1/2) λd/L

Answer

Y = (m + 1) λL/d

Answer

Y = (m + ½) dL/λ

Question 27

27. 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 28

28. 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 29

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

Answer

Of same amplitude

Answer

Have constant phase difference

Answer

Be close to each other

Question 30

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

Answer

Wavelength

Answer

Wave front

Answer

Wave number

Question 31

31. 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

Decreasing the distance between the screen and the slits

Answer

Using monochromatic light of longer wavelength

Answer

Using monochromatic light of higher frequency

Answer

Increasing the distance between the slits

Question 32

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

Question 33

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

Answer

Interference

Answer

Polarization

Answer

Reflection

Answer

Diffraction

Question 34

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

Answer

3 x 10⁸ ms¯¹

Answer

3 x 10¯¹⁰ ms¯¹

Answer

3 x 10⁵ ms¯¹

Answer

3.1 x 10⁸ ms¯¹

Question 35

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

Answer

Polarization

Answer

Destructive interference

Answer

Constructive interference

Answer

Diffraction

Question 36

36. Central spot of New tons rings

Answer

Bright for large wavelength

Answer

Dart for large wavelength

Question 37

37. Can two head lights of car can produce interference

Answer

None of these

Answer

Partly produce interference

Question 38

38. Choose the correct statement

Answer

There is no relationship between rays and wave fronts

Answer

Rays are not normal to wave front

Answer

Rays are normal to wave front

Answer

Rays may be normal to wave front

Question 39

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

Answer

Of same frequency

Answer

Of the same frequency and having definite phase relationship

Answer

Different wavelength

Answer

Of nearly the same frequency

Question 40

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

Answer

Cannot be diffracted

Answer

Cannot be polarized

Answer

Do not affect a photographic plate

Answer

Have a lower frequency

Question 41

41. 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 42

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

Answer

None of these

Question 43

43. A polarizer is used to

Answer

Produce polarized light

Answer

Reduced intensity of light

Answer

Increase intensity of light

Answer

Produce unpolarised light

Question 44

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

Answer

None of these

Answer

Comparable

Answer

Not comparable

Question 45

45. 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 46

46. Which one of the following cannot be polarized?

Answer

Radio waves

Answer

Sound waves

Answer

Ultraviolet rays

Question 47

47. Wavelength of light of frequency 100 Hz is

Answer

5 x 10⁶ m

Answer

3 x 10⁶ m

Answer

4 x 10⁶ m

Answer

2 x 10⁶ m

Question 48

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

Answer

A cylindrical wave front

Answer

A plane wave front

Answer

A spherical wave front

Answer

An elliptical wave front

Question 49

49. In a plane polarized light

Answer

Vibration in two mutually perpendicular directions

Answer

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

Answer

Vibration in all direction

Answer

No vibration at all

Question 50

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

Answer

Coinciding

Answer

Close together

Answer

At a far off distance

Answer

Opposite to each other

Question 51

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

Answer

Increasing gradually

Answer

None of these

Answer

Decreasing gradually

Answer

It is constant at the center

Question 52

52. Ray optics is valid, when characteristic dimensions are

Answer

Much larger than the wavelength of light

Answer

Of the same order as the wavelength of light

Answer

Much smaller than the wavelength of length

Answer

Of the order of one millimeter

Question 53

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

Answer

Intensity ratio of the sources

Answer

Fringe width

Answer

Wavelength

Answer

Distance between the slits

Question 54

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

Answer

Bragg’s law

Answer

Compton effect

Answer

Huygen’s formula

Answer

Laue’s pattern

Question 55

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

Answer

Doppler’s effect

Answer

Diffraction

Answer

Interference

Answer

None of these

Question 56

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

Answer

Reflection

Answer

Origin of spectra

Answer

Diffraction

Answer

Refraction

Question 57

57. Diffraction fringes are

Answer

Distance between then decreases

Answer

Distance between them increases

Answer

They are adjacent with no space in between

Answer

Equally spaced

Question 58

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

Question 59

59. Crystals of a material can behave as

Answer

Convex lens

Answer

Diffraction grating

Answer

Interferometer

Question 60

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

Answer

Wavelength

Answer

Wave front

Question 61

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

Answer

Interference of light

Answer

Diffraction of light

Answer

Reflection of light

Answer

None of these

Question 62

62. 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

Interference pattern produced due to thin oil film

Answer

Total internal reflection of light

Question 63

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

Answer

Diffraction

Answer

Refraction

Answer

Origin of spectra

Answer

Reflection

Question 64

64. 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

Answer 212

Transmission

Answer 213

Absorption

Answer 214

Diffraction

Answer 215

Polarization

Answer 216

5 x 10⁵ to 5 x 10¹¹ Hz

Answer 217

5 x 10⁵ to 5 x 10⁵ Hz

Answer 218

5 x 10¹¹ to 5 x 10¹⁴ Hz

Answer 219

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Answer 220

Continuous emission spectrum

Answer 221

Emission spectrum

Answer 222

Line spectrum

Answer 223

All of these

Answer 224

An electromagnetic wave

Answer 225

A transverse waves

Answer 226

A sound wave

Answer 227

A longitudinal wave

Answer 228

Electromagnetic

Answer 229

In the form of a narrow beam

Answer 230

Monochromatic

Answer 231

Incoherent

Answer 232

Remains the same

Answer 233

None of these

Answer 234

Plano-convex

Answer 235

Convexo-concave

Answer 236

Double-convex

Answer 237

Plano-concave

Answer 238

Both reflected and refracted light

Answer 239

Refracted light

Answer 240

Reflected light

Answer 241

Neither reflected nor refracted light

Answer 242

Colored fringes will be seen

Answer 243

Impossible to predict

Answer 244

Alternate dark and bright fringes will be seen

Answer 245

No interference fringes will be seen

Answer 246

Diffraction pattern

Answer 247

Interference pattern produced due to thin oil film

Answer 248

Total internal reflection of light

Answer 249

Polarization

Answer 250

Equal width

Answer 251

None of these

Answer 252

Different width

Answer 253

Dark fringes are thicker than bright

Answer 254

Cosmic-rays

Answer 255

Ultra-violet rays

Answer 256

It is reflected by the atmosphere

Answer 257

Its velocity is very large

Answer 258

It is not absorbed by the atmosphere

Answer 259

Its wavelength is very small

Answer 260

Same wave length with constant phase difference

Answer 261

Same amplitude of vibration

Answer 262

Same wavelength

Answer 263

Same amplitude and wavelength

Answer 264

Wavelength

Answer 265

All of these

Answer 266

(m – 1)λ

Answer 267

Reflection

Answer 268

Dispersion

Answer 269

Refraction

Answer 270

Interference

Answer 271

Diffraction

Answer 272

Reflection

Answer 273

Refraction

Answer 274

Transmission

Answer 275

Velocity of different colors is different

Answer 276

Amplitude of different colors is different

Answer 277

Energy of different colors is different

Answer 278

Phase of different colors is different

Answer 279

Integral multiple of λ

Answer 280

Integral multiple of λ/2

Answer 281

Even integral multiple of λ

Answer 282

Odd integral multiple of λ/2

Answer 283

Photoelectric effect

Answer 284

Polarization

Answer 285

Diffraction

Answer 286

Interference

Answer 287

Band absorption spectrum

Answer 288

Line absorption spectrum

Answer 289

Line emission spectrum

Answer 290

Band emission spectrum

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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