Physics Lights and Optics Online Mcqs Test

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Question 1

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

Answer

Reflection

Answer

Diffraction

Answer

Refraction

Answer

Transmission

Question 2

2. Light appears to travel in straight lies since

Answer

It is reflected by the atmosphere

Answer

Its wavelength is very small

Answer

Its velocity is very large

Answer

It is not absorbed by the atmosphere

Question 3

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

Answer

Wavelength

Answer

Distance between the slits

Answer

Intensity ratio of the sources

Answer

Fringe width

Question 4

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

Answer

An electromagnetic wave

Answer

A sound wave

Answer

A longitudinal wave

Answer

A transverse waves

Question 5

5. Light on passing through a Polaroid is

Answer

Un-polarized

Answer

Circularly polarized

Answer

Plane polarized

Answer

Elliptically polarized

Question 6

6. 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 7

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

Answer

Reflection

Answer

Interference

Answer

Polarization

Answer

Diffraction

Question 8

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

Answer

None of these

Question 9

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

Answer

Light can be diffracted

Answer

Light can be polarized

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 10

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

Answer

Wavelength

Answer

Wave front

Question 11

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

Answer

3.1 x 10⁸ ms¯¹

Answer

3 x 10¯¹⁰ ms¯¹

Answer

3 x 10⁸ ms¯¹

Answer

3 x 10⁵ ms¯¹

Question 12

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

Question 13

13. Can two head lights of car can produce interference

Answer

None of these

Answer

Partly produce interference

Question 14

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

Answer

Ultrasonics

Answer

Supersonics

Question 15

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

Answer

Electromagnetic

Answer

Incoherent

Answer

Monochromatic

Answer

In the form of a narrow beam

Question 16

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

Answer

Wave front

Answer

Wave number

Answer

Wavelength

Question 17

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

Question 18

18. 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 longer wavelength

Answer

Increasing the distance between the slits

Answer

Decreasing the distance between the screen and the slits

Answer

Using monochromatic light of higher frequency

Question 19

19. 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 20

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

Answer

All of these

Answer

Wavelength

Question 21

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

Answer

Laser rays are high velocity waves

Answer

Laser rays propagate in a straight line

Answer

Laser rays are not absorbed

Answer

Laser rays are most coherent waves

Question 22

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

Answer

2 x 10¯⁵ mm

Answer

5 x 10¯³ mm

Answer

2 x 10¯³ mm

Question 23

23. A polarizer is used to

Answer

Increase intensity of light

Answer

Reduced intensity of light

Answer

Produce unpolarised light

Answer

Produce polarized light

Question 24

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

Question 25

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

Question 26

26. 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 27

27. Huygen’s wave theory of light cannot explain

Answer

Polarization

Answer

Diffraction

Answer

Photoelectric effect

Answer

Interference

Question 28

28. In an interference pattern

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

Answer

Both dark and bright fringes are of equal width

Question 29

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

Answer

2π Sin θ = (m + 1/2)λ

Answer

½ d Sin θ = mλ

Answer

d Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Question 30

30. A spherical wave front is that which has

Answer

A extended source

Answer

A point source

Answer

None of these

Question 31

31. 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 32

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

Answer

Reflection

Answer

Refraction

Answer

Diffraction

Answer

Origin of spectra

Question 33

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

Answer

Interference

Answer

Doppler’s effect

Answer

None of these

Answer

Diffraction

Question 34

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

Answer

Diffraction

Answer

Origin of spectra

Answer

Reflection

Answer

Refraction

Question 35

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

Answer

Incoherent

Answer

In the form of a narrow beam

Answer

Electromagnetic

Answer

Monochromatic

Question 36

36. 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 37

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

Answer

Interference of light

Answer

Diffraction of light

Answer

None of these

Answer

Reflection of light

Question 38

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

Answer

Opposite to each other

Answer

Coinciding

Answer

At a far off distance

Answer

Close together

Question 39

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

Answer

Band absorption spectrum

Answer

Line emission spectrum

Answer

Band emission spectrum

Answer

Line absorption spectrum

Question 40

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

Answer

Speed of propagation greater than wave

Answer

Speed of propagation of the wave

Answer

Speed of propagation less than the wave

Question 41

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

Answer

Comparable

Answer

Not comparable

Answer

None of these

Question 42

42. 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

Decreasing gradually

Answer

None of these

Answer

It is constant at the center

Question 43

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

Answer

Y = (m + 1) λL/d

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + 1/2) λd/L

Answer

Y = (m + ½) dL/λ

Question 44

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

Answer

None of these

Question 45

45. 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

Energy of different colors is different

Answer

Velocity of different colors is different

Answer

Amplitude of different colors is different

Question 46

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

Answer

Plano-convex

Answer

Plano-concave

Answer

Double-convex

Answer

Convexo-concave

Question 47

47. For constructive interference the path difference is

Answer

(m – 1)λ

Question 48

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

Answer

Reflected light

Answer

Both reflected and refracted light

Answer

Neither reflected nor refracted light

Answer

Refracted light

Question 49

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

Answer

Line spectrum

Answer

Continuous emission spectrum

Answer

All of these

Answer

Emission spectrum

Question 50

50. The principle of Michelson’s interferometers is

Answer

Reflection

Answer

Dispersion

Answer

Interference

Answer

Refraction

Question 51

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

Answer

A plane wave front

Answer

An elliptical wave front

Answer

A cylindrical wave front

Answer

A spherical wave front

Question 52

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

Answer

Polarization

Answer

Diffraction

Answer

Constructive interference

Answer

Destructive interference

Question 53

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

Answer

Absorption

Answer

Polarization

Answer

Transmission

Answer

Diffraction

Question 54

54. In the phenomenon of interference, the bright ad dark fringes are of

Answer

Dark fringes are thicker than bright

Answer

None of these

Answer

Different width

Answer

Equal width

Question 55

55. Polarization occurs only in ________ waves

Answer

Mechanical waves

Answer

Longitudinal

Answer

Transverse

Answer

Matter waves

Question 56

56. The blue colour of the sky is due to

Answer

Polarization

Answer

Scattering

Answer

Diffraction

Answer

Reflection

Question 57

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

Answer

Odd integral multiple of λ/2

Answer

Even integral multiple of λ

Answer

Integral multiple of λ

Answer

Integral multiple of λ/2

Question 58

58. 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 59

59. 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 60

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

Answer

Interference with dark bands

Answer

Interference with bright bands

Answer

No interference

Question 61

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

Answer

Alternate dark and bright fringes will be seen

Answer

No interference fringes will be seen

Answer

Colored fringes will be seen

Answer

Impossible to predict

Question 62

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

Answer

None of these

Question 63

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

Answer

Light can be polarized

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

Answer

Light can be diffracted

Question 64

64. Appearance of colour in thin films is due to

Answer

Dispersion

Answer

Polarization

Answer

Interference

Answer

Diffraction

Answer 210

Less for a sharp edge

Answer 211

More for a sharp edge

Answer 212

More for a round edge

Answer 213

Less for a round edge

Answer 214

Radio waves

Answer 215

Sound waves

Answer 216

Ultraviolet rays

Answer 217

None of these

Answer 218

A Plano convex lens and the plane glass plate

Answer 219

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

Answer 220

A Plano convex lens and simple glass sheet

Answer 221

Interference pattern produced due to thin oil film

Answer 222

Total internal reflection of light

Answer 223

Diffraction pattern

Answer 224

Polarization

Answer 225

5 x 10⁵ to 5 x 10⁵ Hz

Answer 226

5 x 10¹¹ to 5 x 10¹⁴ Hz

Answer 227

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Answer 228

5 x 10⁵ to 5 x 10¹¹ Hz

Answer 229

Cosmic-rays

Answer 230

Ultra-violet rays

Answer 231

Thomos young

Answer 232

Do not affect a photographic plate

Answer 233

Have a lower frequency

Answer 234

Cannot be polarized

Answer 235

Cannot be diffracted

Answer 236

Source of wave front

Answer 237

None of these

Answer 238

Source of secondary wave front

Answer 239

Bright for large wavelength

Answer 240

Dart for large wavelength

Answer 241

Reflection

Answer 242

Diffraction

Answer 243

Refraction

Answer 244

Interference

Answer 245

Same wavelength

Answer 246

Same wave length with constant phase difference

Answer 247

Same amplitude and wavelength

Answer 248

Same amplitude of vibration

Answer 249

Remains the same

Answer 250

None of these

Answer 251

Vibration in all direction

Answer 252

No vibration at all

Answer 253

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

Answer 254

Vibration in two mutually perpendicular directions

Answer 255

d sin θ = 2λm

Answer 256

md cos θ = λ

Answer 257

d sin θ = mλ

Answer 258

d sin θ = m/2 λ

Answer 259

Refraction

Answer 260

Polarization

Answer 261

Diffraction

Answer 262

Reflection

Answer 263

A half-period zone

Answer 264

Wave front

Answer 265

Of same frequency

Answer 266

Different wavelength

Answer 267

Of nearly the same frequency

Answer 268

Of the same frequency and having definite phase relationship

Answer 269

Refraction

Answer 270

Total internal reflection

Answer 271

Scattering

Answer 272

Reflection

Answer 273

5 x 10⁶ m

Answer 274

2 x 10⁶ m

Answer 275

4 x 10⁶ m

Answer 276

3 x 10⁶ m

Answer 277

Laue’s pattern

Answer 278

Compton effect

Answer 279

Huygen’s formula

Answer 280

Bragg’s law

Answer 281

Polarization

Answer 282

Interference

Answer 283

Diffraction

Answer 284

Photoelectric effect

Answer 285

Of same amplitude

Answer 286

Be close to each other

Answer 287

Have constant phase difference

Answer 288

Interferometer

Answer 289

Convex lens

Answer 290

Diffraction grating

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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