Physics Lights and Optics Online Mcqs Test

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Question 1

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

Answer

Refraction

Answer

Diffraction

Answer

Origin of spectra

Answer

Reflection

Question 2

2. 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 3

3. 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

Light can be polarized

Answer

Light can be diffracted

Answer

Two coherent light waves can be made to interfere

Question 4

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

Answer

Polarization

Answer

Diffraction

Answer

Transmission

Answer

Absorption

Question 5

5. Which one of the following cannot be polarized?

Answer

Sound waves

Answer

Ultraviolet rays

Answer

Radio waves

Question 6

6. Which of the following has least wavelength?

Answer

Cosmic-rays

Answer

Ultra-violet rays

Question 7

7. In an interference pattern

Answer

Both dark and bright fringes are of equal width

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

Question 8

8. Can two head lights of car can produce interference

Answer

None of these

Answer

Partly produce interference

Question 9

9. Light appears to travel in straight lies since

Answer

Its velocity is very large

Answer

Its wavelength is very small

Answer

It is reflected by the atmosphere

Answer

It is not absorbed by the atmosphere

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. 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 12

12. The blue colour of the sky is due to

Answer

Reflection

Answer

Diffraction

Answer

Scattering

Answer

Polarization

Question 13

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

Answer

Monochromatic

Answer

Electromagnetic

Answer

Incoherent

Answer

In the form of a narrow beam

Question 14

14. 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 10⁵ to 5 x 10⁵ Hz

Answer

5 x 10⁵ to 5 x 10¹¹ Hz

Answer

5 x 10¹⁴ to 5 x 10¹⁷ Hz

Answer

5 x 10¹¹ to 5 x 10¹⁴ Hz

Question 15

15. 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 16

16. 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

Diffraction

Answer

None of these

Question 17

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

Question 18

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

Answer

None of these

Answer

Not comparable

Answer

Comparable

Question 19

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

Answer

Integral multiple of λ

Answer

Even integral multiple of λ

Answer

Integral multiple of λ/2

Answer

Odd integral multiple of λ/2

Question 20

20. 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 21

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

Answer

Refraction

Answer

Diffraction

Answer

Origin of spectra

Answer

Reflection

Question 22

22. The cause of mirage observed in desert is

Answer

Total internal reflection

Answer

Reflection

Answer

Refraction

Answer

Scattering

Question 23

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

Answer

Band absorption spectrum

Answer

Line absorption spectrum

Answer

Line emission spectrum

Answer

Band emission spectrum

Question 24

24. 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

Increasing the distance between the slits

Answer

Using monochromatic light of longer wavelength

Question 25

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

Answer

Equal width

Answer

None of these

Answer

Different width

Answer

Dark fringes are thicker than bright

Question 26

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

Answer

Monochromatic

Answer

Incoherent

Answer

In the form of a narrow beam

Answer

Electromagnetic

Question 27

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

Answer

Do not affect a photographic plate

Answer

Cannot be polarized

Answer

Have a lower frequency

Answer

Cannot be diffracted

Question 28

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

Answer

All of these

Answer

Wavelength

Question 29

29. 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 30

30. Huygen’s wave theory of light cannot explain

Answer

Polarization

Answer

Diffraction

Answer

Photoelectric effect

Answer

Interference

Question 31

31. 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 32

32. Polarization occurs only in ________ waves

Answer

Longitudinal

Answer

Transverse

Answer

Mechanical waves

Answer

Matter waves

Question 33

33. Ray optics is valid, when characteristic dimensions are

Answer

Of the order of one millimeter

Answer

Much smaller than the wavelength of length

Answer

Of the same order as the wavelength of light

Answer

Much larger than the wavelength of light

Question 34

34. Huygen’s wave theory of light cannot explain

Answer

Polarization

Answer

Photoelectric effect

Answer

Interference

Answer

Diffraction

Question 35

35. Central spot of New tons rings

Answer

Dart for large wavelength

Answer

Bright for large wavelength

Question 36

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

Question 37

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

Answer

Huygen’s formula

Answer

Bragg’s law

Answer

Laue’s pattern

Answer

Compton effect

Question 38

38. Wavelength of light of frequency 100 Hz is

Answer

5 x 10⁶ m

Answer

4 x 10⁶ m

Answer

3 x 10⁶ m

Answer

2 x 10⁶ m

Question 39

39. A spherical wave front is that which has

Answer

A extended source

Answer

None of these

Answer

A point source

Question 40

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

Answer

Ultrasonics

Answer

Supersonics

Question 41

41. A polarizer is used to

Answer

Increase intensity of light

Answer

Produce polarized light

Answer

Produce unpolarised light

Answer

Reduced intensity of light

Question 42

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

Answer

None of these

Answer

Source of secondary wave front

Answer

Source of wave front

Question 43

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

Answer

Different wavelength

Answer

Of same frequency

Answer

Of the same frequency and having definite phase relationship

Answer

Of nearly the same frequency

Question 44

44. Longitudinal waves do not exhibit

Answer

Reflection

Answer

Diffraction

Answer

Polarization

Answer

Refraction

Question 45

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

Answer

A transverse waves

Answer

An electromagnetic wave

Answer

A longitudinal wave

Answer

A sound wave

Question 46

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

Answer

None of these

Question 47

47. Crystals of a material can behave as

Answer

Interferometer

Answer

Diffraction grating

Answer

Convex lens

Question 48

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

Answer

Plano-concave

Answer

Double-convex

Answer

Convexo-concave

Answer

Plano-convex

Question 49

49. Light on passing through a Polaroid is

Answer

Circularly polarized

Answer

Un-polarized

Answer

Elliptically polarized

Answer

Plane polarized

Question 50

50. For constructive interference the path difference is

Answer

(m – 1)λ

Question 51

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

Answer

Reflection

Answer

Interference

Answer

Polarization

Answer

Diffraction

Question 52

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

Answer

Transmission

Answer

Diffraction

Answer

Reflection

Answer

Refraction

Question 53

53. 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 54

54. 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

It is constant at the center

Answer

None of these

Answer

Decreasing gradually

Question 55

55. 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 56

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

Answer

Neither reflected nor refracted light

Answer

Refracted light

Answer

Both reflected and refracted light

Answer

Reflected light

Question 57

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

Answer

An elliptical wave front

Answer

A spherical wave front

Answer

A cylindrical wave front

Answer

A plane wave front

Question 58

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

Question 59

59. The idea of light as wave produced by

Answer

Thomos young

Question 60

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

Answer

Y = (m + 1/2) λL/d

Answer

Y = (m + ½) dL/λ

Answer

Y = (m + 1/2) λd/L

Answer

Y = (m + 1) λL/d

Question 61

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

Answer

Wave front

Answer

Wave number

Answer

Wavelength

Question 62

62. Choose the correct statement

Answer

There is no relationship between rays and wave fronts

Answer

Rays are normal to wave front

Answer

Rays are not normal to wave front

Answer

Rays may be normal to wave front

Question 63

63. 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

Interference pattern produced due to thin oil film

Answer

Total internal reflection of light

Answer

Polarization

Answer

Diffraction pattern

Question 64

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

Answer

Laser rays are most coherent waves

Answer

Laser rays are high velocity waves

Answer

Laser rays propagate in a straight line

Answer

Laser rays are not absorbed

Answer 208

m Sin θ = (d + 1/2)λ

Answer 209

½ d Sin θ = mλ

Answer 210

2π Sin θ = (m + 1/2)λ

Answer 211

d Sin θ = (m + 1/2)λ

Answer 212

Interference

Answer 213

Diffraction

Answer 214

Polarization

Answer 215

Dispersion

Answer 216

None of these

Answer 217

Wavelength

Answer 218

Intensity ratio of the sources

Answer 219

Distance between the slits

Answer 220

Fringe width

Answer 221

More for a round edge

Answer 222

Less for a sharp edge

Answer 223

Less for a round edge

Answer 224

More for a sharp edge

Answer 225

Interference

Answer 226

Reflection

Answer 227

Dispersion

Answer 228

Refraction

Answer 229

No interference fringes will be seen

Answer 230

Impossible to predict

Answer 231

Colored fringes will be seen

Answer 232

Alternate dark and bright fringes will be seen

Answer 233

Vibration in all direction

Answer 234

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

Answer 235

Vibration in two mutually perpendicular directions

Answer 236

No vibration at all

Answer 237

Same amplitude of vibration

Answer 238

Same amplitude and wavelength

Answer 239

Same wave length with constant phase difference

Answer 240

Same wavelength

Answer 241

Polarization

Answer 242

Diffraction

Answer 243

Constructive interference

Answer 244

Destructive interference

Answer 245

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

Answer 246

A Plano convex lens and simple glass sheet

Answer 247

None of these

Answer 248

A Plano convex lens and the plane glass plate

Answer 249

d sin θ = m/2 λ

Answer 250

md cos θ = λ

Answer 251

d sin θ = 2λm

Answer 252

d sin θ = mλ

Answer 253

Remains the same

Answer 254

None of these

Answer 255

Have constant phase difference

Answer 256

Be close to each other

Answer 257

Of same amplitude

Answer 258

None of these

Answer 259

Energy of different colors is different

Answer 260

Velocity of different colors is different

Answer 261

Phase of different colors is different

Answer 262

Amplitude of different colors is different

Answer 263

They are adjacent with no space in between

Answer 264

Equally spaced

Answer 265

Distance between them increases

Answer 266

Distance between then decreases

Answer 267

None of these

Answer 268

Diffraction of light

Answer 269

Reflection of light

Answer 270

Interference of light

Answer 271

3 x 10⁸ ms¯¹

Answer 272

3.1 x 10⁸ ms¯¹

Answer 273

3 x 10⁵ ms¯¹

Answer 274

3 x 10¯¹⁰ ms¯¹

Answer 275

Opposite to each other

Answer 276

Close together

Answer 277

Coinciding

Answer 278

At a far off distance

Answer 279

Diffraction pattern

Answer 280

Polarization

Answer 281

Total internal reflection of light

Answer 282

Interference pattern produced due to thin oil film

Answer 283

Interference in which breadth of the fringe will be slightly increase

Answer 284

Interference with bright bands

Answer 285

No interference

Answer 286

Interference with dark bands

Answer 287

Continuous emission spectrum

Answer 288

All of these

Answer 289

Emission spectrum

Answer 290

Line 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

Physics Lights and Optics Practice Test Online With Explanation

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