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

Transmission

Answer

Refraction

Answer

Diffraction

Answer

Reflection

Question 2

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

Answer

Diffraction

Answer

Reflection

Answer

Refraction

Answer

Interference

Question 3

3. 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 4

4. 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 10¹¹ Hz

Answer

5 x 10⁵ to 5 x 10⁵ Hz

Answer

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Question 5

5. In an interference pattern

Answer

Central fringes are brighter than the outer fringes

Answer

Bright fringes are wider than dark fringes

Answer

Dark fringes are wider than bright fringe

Answer

Both dark and bright fringes are of equal width

Question 6

6. Appearance of colour in thin films is due to

Answer

Diffraction

Answer

Interference

Answer

Polarization

Answer

Dispersion

Question 7

7. In a plane polarized light

Answer

No vibration at all

Answer

Vibration in two mutually perpendicular directions

Answer

Vibration in all direction

Answer

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

Question 8

8. Ray optics is valid, when characteristic dimensions are

Answer

Much smaller than the wavelength of length

Answer

Much larger than the wavelength of light

Answer

Of the same order as the wavelength of light

Answer

Of the order of one millimeter

Question 9

9. 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

Using monochromatic light of higher frequency

Answer

Decreasing the distance between the screen and the slits

Answer

Using monochromatic light of longer wavelength

Question 10

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

Answer

d sin θ = (m + 1/2)π/λ

Answer

d sin θ = (m + 1/2)λ

Answer

d in θ = (m + ½ )1/λ

Answer

d sin θ = (m + 1)λ

Question 11

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

Answer

Y = (m + 1/2) λd/L

Answer

Y = (m + ½) dL/λ

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + 1) λL/d

Question 12

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

Answer

Wavelength

Answer

Distance between the slits

Answer

Fringe width

Answer

Intensity ratio of the sources

Question 13

13. 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

Interference pattern produced due to thin oil film

Answer

Total internal reflection of light

Question 14

14. The blue colour of the sky is due to

Answer

Reflection

Answer

Scattering

Answer

Polarization

Answer

Diffraction

Question 15

15. 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 16

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

Answer

Refraction

Answer

Origin of spectra

Answer

Diffraction

Answer

Reflection

Question 17

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

Answer

Different width

Answer

None of these

Answer

Equal width

Answer

Dark fringes are thicker than bright

Question 18

18. Light on passing through a Polaroid is

Answer

Elliptically polarized

Answer

Plane polarized

Answer

Circularly polarized

Answer

Un-polarized

Question 19

19. Choose the correct statement

Answer

Rays are normal to wave front

Answer

Rays are not normal to wave front

Answer

Rays may be normal to wave front

Answer

There is no relationship between rays and wave fronts

Question 20

20. The idea of light as wave produced by

Answer

Thomos young

Question 21

21. 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 22

22. 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 23

23. 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 24

24. 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

Polarization

Answer

Diffraction pattern

Answer

Interference pattern produced due to thin oil film

Question 25

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

Answer

All of these

Answer

Continuous emission spectrum

Answer

Line spectrum

Answer

Emission spectrum

Question 26

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

Answer

At a far off distance

Answer

Coinciding

Answer

Opposite to each other

Answer

Close together

Question 27

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

Answer

Of the same frequency and having definite phase relationship

Answer

Different wavelength

Answer

Of same frequency

Answer

Of nearly the same frequency

Question 28

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

Answer

Plano-convex

Answer

Double-convex

Answer

Convexo-concave

Answer

Plano-concave

Question 29

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

Answer

Diffraction

Answer

Interference

Answer

None of these

Answer

Doppler’s effect

Question 30

30. The fringe spacing in case of blue light

Answer

None of these

Answer

Remains the same

Question 31

31. 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 32

32. Light appears to travel in straight lies since

Answer

It is reflected by the atmosphere

Answer

It is not absorbed by the atmosphere

Answer

Its wavelength is very small

Answer

Its velocity is very large

Question 33

33. The cause of mirage observed in desert is

Answer

Refraction

Answer

Reflection

Answer

Total internal reflection

Answer

Scattering

Question 34

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

Answer

Integral multiple of λ

Answer

Odd integral multiple of λ/2

Answer

Even integral multiple of λ

Answer

Integral multiple of λ/2

Question 35

35. Huygen’s wave theory of light cannot explain

Answer

Polarization

Answer

Photoelectric effect

Answer

Diffraction

Answer

Interference

Question 36

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

Answer

Cannot be polarized

Answer

Cannot be diffracted

Answer

Do not affect a photographic plate

Answer

Have a lower frequency

Question 37

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

Answer

Not comparable

Answer

Comparable

Answer

None of these

Question 38

38. Which one of the following cannot be polarized?

Answer

Sound waves

Answer

Ultraviolet rays

Answer

Radio waves

Question 39

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

Answer

None of these

Question 40

40. The principle of Michelson’s interferometers is

Answer

Refraction

Answer

Interference

Answer

Dispersion

Answer

Reflection

Question 41

41. Central spot of New tons rings

Answer

Bright for large wavelength

Answer

Dart for large wavelength

Question 42

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

Answer

Diffraction

Answer

Constructive interference

Answer

Polarization

Answer

Destructive interference

Question 43

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

Answer

Both reflected and refracted light

Answer

Reflected light

Answer

Refracted light

Answer

Neither reflected nor refracted light

Question 44

44. Diffraction fringes are

Answer

Equally spaced

Answer

Distance between them increases

Answer

They are adjacent with no space in between

Answer

Distance between then decreases

Question 45

45. 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 46

46. 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 47

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

Answer

Transmission

Answer

Polarization

Answer

Diffraction

Answer

Absorption

Question 48

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

Answer

Wave number

Answer

Wave front

Answer

Wavelength

Question 49

49. Which of the following has least wavelength?

Answer

Cosmic-rays

Answer

Ultra-violet rays

Question 50

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

Answer

d sin θ = m/2 λ

Answer

md cos θ = λ

Answer

d sin θ = mλ

Answer

d sin θ = 2λm

Question 51

51. A spherical wave front is that which has

Answer

A point source

Answer

A extended source

Answer

None of these

Question 52

52. 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 53

53. A polarizer is used to

Answer

Produce polarized light

Answer

Increase intensity of light

Answer

Reduced intensity of light

Answer

Produce unpolarised light

Question 54

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

Answer

Same amplitude of vibration

Answer

Same amplitude and wavelength

Answer

Same wave length with constant phase difference

Answer

Same wavelength

Question 55

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

Question 56

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

Answer

Diffraction

Answer

Refraction

Answer

Origin of spectra

Answer

Reflection

Question 57

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

Answer

All of these

Answer

Wavelength

Question 58

58. Diffraction effect is

Answer

Less for a round edge

Answer

Less for a sharp edge

Answer

More for a round edge

Answer

More for a sharp edge

Question 59

59. Huygen’s wave theory of light cannot explain

Answer

Interference

Answer

Photoelectric effect

Answer

Diffraction

Answer

Polarization

Question 60

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

Question 61

61. Wavelength of light of frequency 100 Hz is

Answer

5 x 10⁶ m

Answer

2 x 10⁶ m

Answer

4 x 10⁶ m

Answer

3 x 10⁶ m

Question 62

62. Longitudinal waves do not exhibit

Answer

Reflection

Answer

Refraction

Answer

Diffraction

Answer

Polarization

Question 63

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

Answer

Monochromatic

Answer

Incoherent

Answer

Electromagnetic

Answer

In the form of a narrow beam

Question 64

64. Polarization occurs only in ________ waves

Answer

Matter waves

Answer

Mechanical waves

Answer

Longitudinal

Answer

Transverse

Answer 225

Laser rays propagate in a straight line

Answer 226

Laser rays are high velocity waves

Answer 227

Laser rays are not absorbed

Answer 228

Laser rays are most coherent waves

Answer 229

Phase of different colors is different

Answer 230

Amplitude of different colors is different

Answer 231

Energy of different colors is different

Answer 232

Velocity of different colors is different

Answer 233

Huygen’s formula

Answer 234

Bragg’s law

Answer 235

Laue’s pattern

Answer 236

Compton effect

Answer 237

2π Sin θ = (m + 1/2)λ

Answer 238

½ d Sin θ = mλ

Answer 239

d Sin θ = (m + 1/2)λ

Answer 240

m Sin θ = (d + 1/2)λ

Answer 241

Partly produce interference

Answer 242

None of these

Answer 243

Band absorption spectrum

Answer 244

Band emission spectrum

Answer 245

Line absorption spectrum

Answer 246

Line emission spectrum

Answer 247

Light can be polarized

Answer 248

Two coherent light waves can be made to interfere

Answer 249

The intensity of light from a point source falls off inversely as the square of the distance from the source

Answer 250

Light can be diffracted

Answer 251

Ultrasonics

Answer 252

Supersonics

Answer 253

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

Answer 254

A Plano convex lens and the plane glass plate

Answer 255

A Plano convex lens and simple glass sheet

Answer 256

None of these

Answer 257

Wave front

Answer 258

Wavelength

Answer 259

3 x 10¯¹⁰ ms¯¹

Answer 260

3 x 10⁵ ms¯¹

Answer 261

3.1 x 10⁸ ms¯¹

Answer 262

3 x 10⁸ ms¯¹

Answer 263

None of these

Answer 264

None of these

Answer 265

Source of secondary wave front

Answer 266

Source of wave front

Answer 267

Elliptical

Answer 268

Two coherent light waves can be made to interfere

Answer 269

Light can be diffracted

Answer 270

Light can be polarized

Answer 271

The intensity of light from a point source falls off inversely as the square of the distance from the source

Answer 272

(m – 1)λ

Answer 273

A transverse waves

Answer 274

A longitudinal wave

Answer 275

An electromagnetic wave

Answer 276

A sound wave

Answer 277

None of these

Answer 278

Interference

Answer 279

Diffraction

Answer 280

Reflection

Answer 281

Polarization

Answer 282

Colored fringes will be seen

Answer 283

No interference fringes will be seen

Answer 284

Impossible to predict

Answer 285

Alternate dark and bright fringes will be seen

Answer 286

Diffraction grating

Answer 287

Interferometer

Answer 288

Convex lens

Answer 289

Wave front

Answer 290

A half-period zone

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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Maan Ali

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