Physics Lights and Optics Online Mcqs Test

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Question 1

1. 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 2

2. 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 bright bands

Answer

No interference

Answer

Interference with dark bands

Question 3

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

Answer

Close together

Answer

At a far off distance

Answer

Opposite to each other

Answer

Coinciding

Question 4

4. The principle of Michelson’s interferometers is

Answer

Dispersion

Answer

Interference

Answer

Reflection

Answer

Refraction

Question 5

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

Answer

Band emission spectrum

Answer

Band absorption spectrum

Answer

Line emission spectrum

Answer

Line absorption spectrum

Question 6

6. 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 7

7. The cause of mirage observed in desert is

Answer

Scattering

Answer

Total internal reflection

Answer

Reflection

Answer

Refraction

Question 8

8. 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

Interference pattern produced due to thin oil film

Answer

Polarization

Answer

Total internal reflection of light

Question 9

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

Answer

Same amplitude and wavelength

Answer

Same wavelength

Answer

Same wave length with constant phase difference

Answer

Same amplitude of vibration

Question 10

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

Answer

3 x 10⁵ ms¯¹

Answer

3 x 10¯¹⁰ ms¯¹

Answer

3 x 10⁸ ms¯¹

Answer

3.1 x 10⁸ ms¯¹

Question 11

11. Crystals of a material can behave as

Answer

Diffraction grating

Answer

Convex lens

Answer

Interferometer

Question 12

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

Answer

Bragg’s law

Answer

Compton effect

Answer

Laue’s pattern

Answer

Huygen’s formula

Question 13

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

Answer

Source of secondary wave front

Answer

Source of wave front

Answer

None of these

Question 14

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

Answer

Two coherent light waves can be made to interfere

Answer

Light can be diffracted

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 polarized

Question 15

15. Ray optics is valid, when characteristic dimensions are

Answer

Much smaller than the wavelength of length

Answer

Of the order of one millimeter

Answer

Of the same order as the wavelength of light

Answer

Much larger than the wavelength of light

Question 16

16. The fringe spacing in case of blue light

Answer

Remains the same

Answer

None of these

Question 17

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

Answer

Diffraction

Answer

Destructive interference

Answer

Constructive interference

Answer

Polarization

Question 18

18. 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 19

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

Answer

Wavelength

Answer

Wave front

Question 20

20. The blue colour of the sky is due to

Answer

Scattering

Answer

Polarization

Answer

Reflection

Answer

Diffraction

Question 21

21. 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 = 2λm

Answer

md cos θ = λ

Answer

d sin θ = m/2 λ

Question 22

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

Question 23

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

Answer

Colored fringes will be seen

Answer

Alternate dark and bright fringes will be seen

Answer

No interference fringes will be seen

Answer

Impossible to predict

Question 24

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

Answer

It is constant at the center

Answer

None of these

Answer

Increasing gradually

Answer

Decreasing gradually

Question 25

25. 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 26

26. Can two head lights of car can produce interference

Answer

Partly produce interference

Answer

None of these

Question 27

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

Answer

None of these

Question 28

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

Answer

½ d Sin θ = mλ

Answer

m Sin θ = (d + 1/2)λ

Answer

2π Sin θ = (m + 1/2)λ

Answer

d Sin θ = (m + 1/2)λ

Question 29

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

Answer

Absorption

Answer

Transmission

Answer

Polarization

Answer

Diffraction

Question 30

30. Diffraction fringes are

Answer

They are adjacent with no space in between

Answer

Equally spaced

Answer

Distance between them increases

Answer

Distance between then decreases

Question 31

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

Answer

Supersonics

Answer

Ultrasonics

Question 32

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

Answer

Laser rays are high velocity waves

Answer

Laser rays are not absorbed

Answer

Laser rays propagate in a straight line

Answer

Laser rays are most coherent waves

Question 33

33. 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 34

34. In a plane polarized light

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

Answer

Vibration in two mutually perpendicular directions

Question 35

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

Answer

d sin θ = (m + 1)λ

Answer

d sin θ = (m + 1/2)λ

Answer

d sin θ = (m + 1/2)π/λ

Answer

d in θ = (m + ½ )1/λ

Question 36

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

Answer

All of these

Answer

Emission spectrum

Answer

Continuous emission spectrum

Answer

Line spectrum

Question 37

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

Answer

None of these

Question 38

38. Diffraction effect is

Answer

More for a round edge

Answer

Less for a round edge

Answer

More for a sharp edge

Answer

Less for a sharp edge

Question 39

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

Answer

Wavelength

Answer

All of these

Question 40

40. 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 higher frequency

Answer

Decreasing the distance between the screen and the slits

Answer

Using monochromatic light of longer wavelength

Answer

Increasing the distance between the slits

Question 41

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

Answer

Reflection

Answer

Transmission

Answer

Refraction

Answer

Diffraction

Question 42

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

Question 43

43. Huygen’s wave theory of light cannot explain

Answer

Photoelectric effect

Answer

Diffraction

Answer

Polarization

Answer

Interference

Question 44

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

Answer

Be close to each other

Answer

Of same amplitude

Answer

Have constant phase difference

Question 45

45. 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

Phase of different colors is different

Answer

Amplitude of different colors is different

Question 46

46. Appearance of colour in thin films is due to

Answer

Interference

Answer

Dispersion

Answer

Polarization

Answer

Diffraction

Question 47

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

Answer

Refraction

Answer

Reflection

Answer

Diffraction

Answer

Interference

Question 48

48. 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 49

49. 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 50

50. The idea of light as wave produced by

Answer

Thomos young

Question 51

51. 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 52

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

Answer

Reflection

Answer

Diffraction

Answer

Refraction

Answer

Origin of spectra

Question 53

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

Answer

Wave number

Answer

Wavelength

Answer

Wave front

Question 54

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

Answer

Light can be diffracted

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

Question 55

55. Light on passing through a Polaroid is

Answer

Circularly polarized

Answer

Un-polarized

Answer

Elliptically polarized

Answer

Plane polarized

Question 56

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

Answer

Interference

Answer

Diffraction

Answer

Reflection

Answer

Polarization

Question 57

57. Polarization occurs only in ________ waves

Answer

Matter waves

Answer

Mechanical waves

Answer

Longitudinal

Answer

Transverse

Question 58

58. 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) λL/d

Answer

Y = (m + 1/2) λL/d

Question 59

59. Huygen’s wave theory of light cannot explain

Answer

Photoelectric effect

Answer

Polarization

Answer

Diffraction

Answer

Interference

Question 60

60. 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 61

61. 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

Of nearly the same frequency

Answer

Different wavelength

Question 62

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

Answer

Dark fringes are thicker than bright

Answer

None of these

Answer

Equal width

Answer

Different width

Question 63

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

Answer

Reflection

Answer

Refraction

Answer

Origin of spectra

Answer

Diffraction

Question 64

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

Answer

Integral multiple of λ

Answer

Integral multiple of λ/2

Answer

Even integral multiple of λ

Answer

Odd integral multiple of λ/2

Answer 220

Comparable

Answer 221

None of these

Answer 222

Not comparable

Answer 223

A spherical wave front

Answer 224

A plane wave front

Answer 225

A cylindrical wave front

Answer 226

An elliptical wave front

Answer 227

Bright fringes are wider than dark fringes

Answer 228

Dark fringes are wider than bright fringe

Answer 229

Central fringes are brighter than the outer fringes

Answer 230

Both dark and bright fringes are of equal width

Answer 231

Ultra-violet rays

Answer 232

Cosmic-rays

Answer 233

Distance between the slits

Answer 234

Wavelength

Answer 235

Intensity ratio of the sources

Answer 236

Fringe width

Answer 237

λ = 2π dm

Answer 238

Radio waves

Answer 239

Ultraviolet rays

Answer 240

Sound waves

Answer 241

Diffraction

Answer 242

Reflection

Answer 243

Refraction

Answer 244

Polarization

Answer 245

Cannot be polarized

Answer 246

Do not affect a photographic plate

Answer 247

Have a lower frequency

Answer 248

Cannot be diffracted

Answer 249

Diffraction

Answer 250

Interference

Answer 251

None of these

Answer 252

Doppler’s effect

Answer 253

(m – 1)λ

Answer 254

Increase intensity of light

Answer 255

Produce unpolarised light

Answer 256

Produce polarized light

Answer 257

Reduced intensity of light

Answer 258

A sound wave

Answer 259

A longitudinal wave

Answer 260

A transverse waves

Answer 261

An electromagnetic wave

Answer 262

There is no relationship between rays and wave fronts

Answer 263

Rays are not normal to wave front

Answer 264

Rays are normal to wave front

Answer 265

Rays may be normal to wave front

Answer 266

In the form of a narrow beam

Answer 267

Electromagnetic

Answer 268

Incoherent

Answer 269

Monochromatic

Answer 270

5 x 10⁶ m

Answer 271

3 x 10⁶ m

Answer 272

2 x 10⁶ m

Answer 273

4 x 10⁶ m

Answer 274

Plano-convex

Answer 275

Double-convex

Answer 276

Convexo-concave

Answer 277

Plano-concave

Answer 278

Dart for large wavelength

Answer 279

Bright for large wavelength

Answer 280

Speed of propagation of the wave

Answer 281

Speed of propagation less than the wave

Answer 282

Speed of propagation greater than wave

Answer 283

Reflected light

Answer 284

Refracted light

Answer 285

Neither reflected nor refracted light

Answer 286

Both reflected and refracted light

Answer 287

None of these

Answer 288

None of these

Answer 289

A point source

Answer 290

A extended source

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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