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

Electromagnetic

Answer

Monochromatic

Answer

Incoherent

Answer

In the form of a narrow beam

Question 2

2. 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 3

3. 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 = m/2 λ

Answer

md cos θ = λ

Answer

d sin θ = 2λm

Question 4

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

Answer

Alternate dark and bright fringes will be seen

Answer

Impossible to predict

Answer

Colored fringes will be seen

Answer

No interference fringes will be seen

Question 5

5. 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

Increasing the distance between the slits

Answer

Decreasing the distance between the screen and the slits

Answer

Using monochromatic light of longer wavelength

Answer

Using monochromatic light of higher frequency

Question 6

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

Answer

None of these

Question 7

7. 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

Both reflected and refracted light

Answer

Reflected light

Question 8

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

Answer

Double-convex

Answer

Convexo-concave

Answer

Plano-convex

Answer

Plano-concave

Question 9

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

Answer

Laser rays propagate in a straight line

Answer

Laser rays are high velocity waves

Answer

Laser rays are not absorbed

Answer

Laser rays are most coherent waves

Question 10

10. 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 11

11. 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 12

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

Answer

Wave front

Answer

Wavelength

Question 13

13. Wavelength of light of frequency 100 Hz is

Answer

4 x 10⁶ m

Answer

3 x 10⁶ m

Answer

2 x 10⁶ m

Answer

5 x 10⁶ m

Question 14

14. The idea of light as wave produced by

Answer

Thomos young

Question 15

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

Answer

d Sin θ = (m + 1/2)λ

Answer

½ d Sin θ = mλ

Answer

2π Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Question 16

16. For constructive interference the path difference is

Answer

(m – 1)λ

Question 17

17. 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¯⁵ mm

Answer

2 x 10¯³ mm

Question 18

18. Diffraction effect is

Answer

More for a round edge

Answer

More for a sharp edge

Answer

Less for a round edge

Answer

Less for a sharp edge

Question 19

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

Answer

All of these

Answer

Continuous emission spectrum

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Emission spectrum

Answer

Line spectrum

Question 20

20. In an interference pattern

Answer

Both dark and bright fringes are of equal width

Answer

Dark fringes are wider than bright fringe

Answer

Central fringes are brighter than the outer fringes

Answer

Bright fringes are wider than dark fringes

Question 21

21. The fringe spacing in case of blue light

Answer

None of these

Answer

Remains the same

Question 22

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

Answer

Monochromatic

Answer

In the form of a narrow beam

Answer

Incoherent

Answer

Electromagnetic

Question 23

23. Huygen’s wave theory of light cannot explain

Answer

Diffraction

Answer

Interference

Answer

Photoelectric effect

Answer

Polarization

Question 24

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

Answer

Y = (m + 1) λL/d

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Y = (m + 1/2) λd/L

Answer

Y = (m + ½) dL/λ

Answer

Y = (m + 1/2) λL/d

Question 25

25. The principle of Michelson’s interferometers is

Answer

Refraction

Answer

Reflection

Answer

Interference

Answer

Dispersion

Question 26

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

Answer

None of these

Answer

Increasing gradually

Answer

Decreasing gradually

Answer

It is constant at the center

Question 27

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

Answer

Diffraction

Answer

Doppler’s effect

Answer

None of these

Answer

Interference

Question 28

28. The setting of Newton’s rings is

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

Answer

A Plano convex lens and the plane glass plate

Question 29

29. Huygen’s wave theory of light cannot explain

Answer

Photoelectric effect

Answer

Diffraction

Answer

Interference

Answer

Polarization

Question 30

30. 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 31

31. Polarization occurs only in ________ waves

Answer

Transverse

Answer

Mechanical waves

Answer

Longitudinal

Answer

Matter waves

Question 32

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

Answer

None of these

Question 33

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

Answer

Diffraction

Answer

Refraction

Answer

Reflection

Answer

Interference

Question 34

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

Question 35

35. The blue colour of the sky is due to

Answer

Diffraction

Answer

Polarization

Answer

Reflection

Answer

Scattering

Question 36

36. Diffraction fringes are

Answer

They are adjacent with no space in between

Answer

Distance between them increases

Answer

Distance between then decreases

Answer

Equally spaced

Question 37

37. Choose the correct statement

Answer

Rays are not normal to wave front

Answer

Rays are normal to wave front

Answer

There is no relationship between rays and wave fronts

Answer

Rays may be normal to wave front

Question 38

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

Answer

Refraction

Answer

Origin of spectra

Answer

Reflection

Answer

Diffraction

Question 39

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

Answer

3 x 10⁸ ms¯¹

Answer

3.1 x 10⁸ ms¯¹

Answer

3 x 10⁵ ms¯¹

Answer

3 x 10¯¹⁰ ms¯¹

Question 40

40. 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 41

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

Answer

Polarization

Answer

Absorption

Answer

Transmission

Answer

Diffraction

Question 42

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

Answer

None of these

Question 43

43. Light appears to travel in straight lies since

Answer

It is reflected by the atmosphere

Answer

Its velocity is very large

Answer

Its wavelength is very small

Answer

It is not absorbed by the atmosphere

Question 44

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

Question 45

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

Answer

A longitudinal wave

Answer

A transverse waves

Answer

A sound wave

Answer

An electromagnetic wave

Question 46

46. Light on passing through a Polaroid is

Answer

Circularly polarized

Answer

Elliptically polarized

Answer

Un-polarized

Answer

Plane polarized

Question 47

47. 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

Two coherent light waves can be made to interfere

Answer

Light can be diffracted

Question 48

48. 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 49

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

Answer

Huygen’s formula

Answer

Bragg’s law

Answer

Compton effect

Answer

Laue’s pattern

Question 50

50. A polarizer is used to

Answer

Produce polarized light

Answer

Produce unpolarised light

Answer

Increase intensity of light

Answer

Reduced intensity of light

Question 51

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

Answer

Have a lower frequency

Answer

Cannot be diffracted

Answer

Do not affect a photographic plate

Answer

Cannot be polarized

Question 52

52. 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 53

53. 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 54

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

Answer

All of these

Answer

Wavelength

Question 55

55. In a plane polarized light

Answer

Vibration in all direction

Answer

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

Answer

Vibration in two mutually perpendicular directions

Answer

No vibration at all

Question 56

56. 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 57

57. Can two head lights of car can produce interference

Answer

None of these

Answer

Partly produce interference

Question 58

58. Crystals of a material can behave as

Answer

Diffraction grating

Answer

Convex lens

Answer

Interferometer

Question 59

59. 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 60

60. 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 61

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

Answer

Velocity of different colors is different

Answer

Energy of different colors is different

Answer

Amplitude of different colors is different

Answer

Phase of different colors is different

Question 62

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

Question 63

63. 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 in which breadth of the fringe will be slightly increase

Answer

Interference with bright bands

Answer

No interference

Question 64

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

Answer

A plane wave front

Answer

A spherical wave front

Answer

An elliptical wave front

Answer

A cylindrical wave front

Answer 211

Cosmic-rays

Answer 212

Ultra-violet rays

Answer 213

Constructive interference

Answer 214

Destructive interference

Answer 215

Diffraction

Answer 216

Polarization

Answer 217

Source of wave front

Answer 218

None of these

Answer 219

Source of secondary wave front

Answer 220

Interference

Answer 221

Diffraction

Answer 222

Polarization

Answer 223

Reflection

Answer 224

A extended source

Answer 225

A point source

Answer 226

None of these

Answer 227

None of these

Answer 228

Reflection of light

Answer 229

Diffraction of light

Answer 230

Interference of light

Answer 231

Diffraction

Answer 232

Polarization

Answer 233

Refraction

Answer 234

Reflection

Answer 235

5 x 10¹¹ to 5 x 10¹⁴ Hz

Answer 236

5 x 10⁵ to 5 x 10⁵ Hz

Answer 237

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Answer 238

5 x 10⁵ to 5 x 10¹¹ Hz

Answer 239

Of same amplitude

Answer 240

Be close to each other

Answer 241

Have constant phase difference

Answer 242

Dispersion

Answer 243

Diffraction

Answer 244

Polarization

Answer 245

Interference

Answer 246

Band absorption spectrum

Answer 247

Line absorption spectrum

Answer 248

Line emission spectrum

Answer 249

Band emission spectrum

Answer 250

Even integral multiple of λ

Answer 251

Integral multiple of λ/2

Answer 252

Integral multiple of λ

Answer 253

Odd integral multiple of λ/2

Answer 254

Scattering

Answer 255

Total internal reflection

Answer 256

Refraction

Answer 257

Reflection

Answer 258

Transmission

Answer 259

Reflection

Answer 260

Diffraction

Answer 261

Refraction

Answer 262

Total internal reflection of light

Answer 263

Interference pattern produced due to thin oil film

Answer 264

Polarization

Answer 265

Diffraction pattern

Answer 266

Wavelength

Answer 267

Wave number

Answer 268

Wave front

Answer 269

Different wavelength

Answer 270

Of the same frequency and having definite phase relationship

Answer 271

Of nearly the same frequency

Answer 272

Of same frequency

Answer 273

Ultraviolet rays

Answer 274

Radio waves

Answer 275

Sound waves

Answer 276

At a far off distance

Answer 277

Close together

Answer 278

Coinciding

Answer 279

Opposite to each other

Answer 280

Supersonics

Answer 281

Ultrasonics

Answer 282

Wavelength

Answer 283

Fringe width

Answer 284

Distance between the slits

Answer 285

Intensity ratio of the sources

Answer 286

Bright for large wavelength

Answer 287

Dart for large wavelength

Answer 288

Speed of propagation greater than wave

Answer 289

Speed of propagation less than the wave

Answer 290

Speed of propagation of the wave

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

Physics Lights and Optics Practice Test Online With Explanation

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