Physics Lights and Optics Online Mcqs Test

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Question 1

1. Longitudinal waves do not exhibit

Answer

Diffraction

Answer

Reflection

Answer

Polarization

Answer

Refraction

Question 2

2. A spherical wave front is that which has

Answer

A extended source

Answer

A point source

Answer

None of these

Question 3

3. 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

Odd integral multiple of λ/2

Answer

Integral multiple of λ/2

Question 4

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

Answer

In the form of a narrow beam

Answer

Incoherent

Answer

Monochromatic

Answer

Electromagnetic

Question 5

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

Answer

Wave front

Answer

Wave number

Answer

Wavelength

Question 6

6. Which one of the following cannot be polarized?

Answer

Sound waves

Answer

Ultraviolet rays

Answer

Radio waves

Question 7

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

Answer

None of these

Question 8

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

Answer

Continuous emission spectrum

Answer

All of these

Answer

Emission spectrum

Answer

Line spectrum

Question 9

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

Answer

All of these

Answer

Wavelength

Question 10

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

Answer

d sin θ = (m + 1/2)λ

Answer

d sin θ = (m + 1)λ

Answer

d in θ = (m + ½ )1/λ

Answer

d sin θ = (m + 1/2)π/λ

Question 11

11. Crystals of a material can behave as

Answer

Convex lens

Answer

Interferometer

Answer

Diffraction grating

Question 12

12. 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

Decreasing gradually

Answer

None of these

Question 13

13. Appearance of colour in thin films is due to

Answer

Interference

Answer

Diffraction

Answer

Polarization

Answer

Dispersion

Question 14

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

Answer

In the form of a narrow beam

Answer

Incoherent

Answer

Monochromatic

Answer

Electromagnetic

Question 15

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

Answer

Supersonics

Answer

Ultrasonics

Question 16

16. Diffraction effect is

Answer

Less for a sharp edge

Answer

Less for a round edge

Answer

More for a sharp edge

Answer

More for a round edge

Question 17

17. 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

Decreasing the distance between the screen and the slits

Answer

Increasing the distance between the slits

Answer

Using monochromatic light of longer wavelength

Answer

Using monochromatic light of higher frequency

Question 18

18. 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

Two coherent light waves can be made to interfere

Answer

Light can be diffracted

Question 19

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

Answer

Diffraction

Answer

Interference

Answer

Refraction

Answer

Reflection

Question 20

20. Huygen’s wave theory of light cannot explain

Answer

Interference

Answer

Polarization

Answer

Photoelectric effect

Answer

Diffraction

Question 21

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

Answer

½ d Sin θ = mλ

Answer

d Sin θ = (m + 1/2)λ

Answer

m Sin θ = (d + 1/2)λ

Answer

2π Sin θ = (m + 1/2)λ

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¯³ mm

Answer

5 x 10¯³ mm

Answer

2 x 10¯⁵ mm

Question 23

23. 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 24

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

Answer

A plane wave front

Answer

A spherical wave front

Answer

A cylindrical wave front

Answer

An elliptical wave front

Question 25

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

Question 26

26. A polarizer is used to

Answer

Produce polarized light

Answer

Increase intensity of light

Answer

Produce unpolarised light

Answer

Reduced intensity of light

Question 27

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

Answer

Amplitude of different colors is different

Answer

Phase of different colors is different

Answer

Energy of different colors is different

Answer

Velocity of different colors is different

Question 28

28. Choose the correct statement

Answer

Rays are not normal to wave front

Answer

Rays may be normal to wave front

Answer

Rays are normal to wave front

Answer

There is no relationship between rays and wave fronts

Question 29

29. Central spot of New tons rings

Answer

Dart for large wavelength

Answer

Bright for large wavelength

Question 30

30. Polarization occurs only in ________ waves

Answer

Longitudinal

Answer

Mechanical waves

Answer

Matter waves

Answer

Transverse

Question 31

31. Light appears to travel in straight lies since

Answer

Its velocity is very large

Answer

Its wavelength is very small

Answer

It is not absorbed by the atmosphere

Answer

It is reflected by the atmosphere

Question 32

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

Answer

Wavelength

Answer

Wave front

Question 33

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

Answer

Laue’s pattern

Answer

Bragg’s law

Answer

Huygen’s formula

Answer

Compton effect

Question 34

34. The principle of Michelson’s interferometers is

Answer

Refraction

Answer

Interference

Answer

Dispersion

Answer

Reflection

Question 35

35. The blue colour of the sky is due to

Answer

Reflection

Answer

Scattering

Answer

Diffraction

Answer

Polarization

Question 36

36. 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 10⁵ ms¯¹

Answer

3 x 10⁸ ms¯¹

Question 37

37. Wavelength of light of frequency 100 Hz is

Answer

2 x 10⁶ m

Answer

4 x 10⁶ m

Answer

5 x 10⁶ m

Answer

3 x 10⁶ m

Question 38

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

Answer

Laser rays are not absorbed

Answer

Laser rays propagate in a straight line

Answer

Laser rays are most coherent waves

Answer

Laser rays are high velocity waves

Question 39

39. 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 40

40. 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 41

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

Answer

None of these

Answer

Interference of light

Answer

Reflection of light

Answer

Diffraction of light

Question 42

42. 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 nearly the same frequency

Answer

Of same frequency

Question 43

43. Which of the following has least wavelength?

Answer

Cosmic-rays

Answer

Ultra-violet rays

Question 44

44. 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 45

45. 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 46

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

Question 47

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

Answer

Doppler’s effect

Answer

None of these

Answer

Interference

Answer

Diffraction

Question 48

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

Answer

Plano-concave

Answer

Convexo-concave

Answer

Plano-convex

Answer

Double-convex

Question 49

49. 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

Reflected light

Answer

Both reflected and refracted light

Question 50

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

Question 51

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

Answer

Polarization

Answer

Interference

Answer

Reflection

Answer

Diffraction

Question 52

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

Answer

None of these

Question 53

53. The setting of Newton’s rings is

Answer

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

Answer

None of these

Answer

A Plano convex lens and simple glass sheet

Answer

A Plano convex lens and the plane glass plate

Question 54

54. 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 + ½) dL/λ

Answer

Y = (m + 1/2) λd/L

Question 55

55. Diffraction fringes are

Answer

Distance between them increases

Answer

Equally spaced

Answer

They are adjacent with no space in between

Answer

Distance between then decreases

Question 56

56. The cause of mirage observed in desert is

Answer

Reflection

Answer

Refraction

Answer

Scattering

Answer

Total internal reflection

Question 57

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

Answer

Comparable

Answer

None of these

Answer

Not comparable

Question 58

58. For constructive interference the path difference is

Answer

(m – 1)λ

Question 59

59. 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 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 with dark bands

Answer

No interference

Answer

Interference with bright bands

Answer

Interference in which breadth of the fringe will be slightly increase

Question 61

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

Question 62

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

Answer

Line absorption spectrum

Answer

Band emission spectrum

Answer

Band absorption spectrum

Answer

Line emission spectrum

Question 63

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

Answer

d sin θ = m/2 λ

Answer

d sin θ = 2λm

Answer

md cos θ = λ

Answer

d sin θ = mλ

Question 64

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

Answer

Refraction

Answer

Reflection

Answer

Diffraction

Answer

Origin of spectra

Answer 209

Alternate dark and bright fringes will be seen

Answer 210

Impossible to predict

Answer 211

Colored fringes will be seen

Answer 212

No interference fringes will be seen

Answer 213

Thomos young

Answer 214

None of these

Answer 215

Remains the same

Answer 216

None of these

Answer 217

Equal width

Answer 218

Different width

Answer 219

Dark fringes are thicker than bright

Answer 220

Wave front

Answer 221

A half-period zone

Answer 222

Speed of propagation less than the wave

Answer 223

Speed of propagation greater than wave

Answer 224

Speed of propagation of the wave

Answer 225

Have constant phase difference

Answer 226

Be close to each other

Answer 227

Of same amplitude

Answer 228

Vibration in two mutually perpendicular directions

Answer 229

Vibration in all direction

Answer 230

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

Answer 231

No vibration at all

Answer 232

Fringe width

Answer 233

Distance between the slits

Answer 234

Wavelength

Answer 235

Intensity ratio of the sources

Answer 236

Interference

Answer 237

Diffraction

Answer 238

Polarization

Answer 239

Photoelectric effect

Answer 240

Have a lower frequency

Answer 241

Cannot be diffracted

Answer 242

Do not affect a photographic plate

Answer 243

Cannot be polarized

Answer 244

None of these

Answer 245

Same amplitude of vibration

Answer 246

Same wavelength

Answer 247

Same amplitude and wavelength

Answer 248

Same wave length with constant phase difference

Answer 249

Central fringes are brighter than the outer fringes

Answer 250

Dark fringes are wider than bright fringe

Answer 251

Bright fringes are wider than dark fringes

Answer 252

Both dark and bright fringes are of equal width

Answer 253

Plane polarized

Answer 254

Un-polarized

Answer 255

Circularly polarized

Answer 256

Elliptically polarized

Answer 257

Diffraction

Answer 258

Absorption

Answer 259

Transmission

Answer 260

Polarization

Answer 261

Much larger than the wavelength of light

Answer 262

Of the same order as the wavelength of light

Answer 263

Much smaller than the wavelength of length

Answer 264

Of the order of one millimeter

Answer 265

Destructive interference

Answer 266

Polarization

Answer 267

Constructive interference

Answer 268

Diffraction

Answer 269

Diffraction

Answer 270

Origin of spectra

Answer 271

Reflection

Answer 272

Refraction

Answer 273

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

Answer 274

Light can be diffracted

Answer 275

Light can be polarized

Answer 276

Two coherent light waves can be made to interfere

Answer 277

Polarization

Answer 278

Total internal reflection of light

Answer 279

Diffraction pattern

Answer 280

Interference pattern produced due to thin oil film

Answer 281

Partly produce interference

Answer 282

None of these

Answer 283

Total internal reflection of light

Answer 284

Interference pattern produced due to thin oil film

Answer 285

Polarization

Answer 286

Diffraction pattern

Answer 287

Transmission

Answer 288

Diffraction

Answer 289

Reflection

Answer 290

Refraction

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

Physics

How to Score High in Physics Lights and Optics Online Mcqs Test?

Key Preparation Tips:

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Maan Ali

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