Home/ECAT/ECAT Physics Optics Chapter Test Online

ECAT Physics Optics Chapter Test Online

Mustansar KhanLast Updated: April 18, 2025

Physics Optics Chapter MCQS Online Test

ECAT Physics Electronics Chapter Online Test

Total Questions:	136
Time Allowed:	60 Minutes
Total Marks:	136
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	ECAT Entry Test Physics Online Test Interview Questions about Physics All Universities Entrance Test Recruitments Tests

ECAT Physics Optics Chapter Online Test

Please wait...

Page 1 of 6

Physics

1. Critical angle of light passing from glass to air is minimum for

Green

Yellow

Red

Blue

2. In Huygen’s wave theory, the locus of all points in the same state of vibration is called

Wave front

A ray

A half-period zone

Vibrator

3. If the focal length of objective is 10 mm find its magnification

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

Base

Producer

Origin

Source

5. The cause of mirage observed in desert is

Reflection

Total internal reflection

Scattering

Refraction

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

Laser rays are most coherent waves

Laser rays are high velocity waves

Laser rays propagate in a straight line

Laser rays are not absorbed

7. A double convex lens acts as a diverging lens when the object is

Inside the focus

At the focus

Between f and 2f

All of these

8. For interference to occur, the interfering beams of light must be

Added

Of difference frequencies

White light

Coherent

9. The setting of Newton’s rings is

A Plano convex lens and the plane glass plate

A Plano convex lens and simple glass sheet

None of these

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

10. Ray optics is valid, when characteristic dimensions are

Of the order of one millimeter

Much larger than the wavelength of light

Much smaller than the wavelength of length

Of the same order as the wavelength of light

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

Momentum

Energy

Intensity

Amplitude

12. In Young’s double slit experiment, the separation between the slit is halved and distance between the slit and screen is doubled. The fringe width is

Halved

Doubled

Unchanged

Quadrupled

13. Geometrical optics cannot give following characteristics for a microscope

Image position

Any of the above

Image size

Resolution of image

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

Amplitude of different colors is different

Energy of different colors is different

Phase of different colors is different

Velocity of different colors is different

15. When the two surfaces of a thin film are parallel and the light is incident at a certain angle, ________ fringes are formed.

Circular

Parabolic

Elliptical

Straight

16. In multimode step index fiber the refractive index of core and cladding is

Different

Zero

Different with refractive index of core higher than cladding

Same

17. Diopter power of an concave lens of 10 cm focal length is

2/10 diopter

11 diopter

1/10 diopter

10 diopter

18. For obtaining equal and same height, mirror should be

Concave

Convex

None

Plane

19. For the normal setting of a telescope

Only the object is at infinity

Only the final image is at infinity

Both the object and the final image is at infinity

Neither the object nor the final image has to be at infinity

20. Just before setting, the sun may appear to be elliptical. This happens due to

Diffraction

Refraction

Reflection

Dispersion

21. Choose the correct statement

Raya may be normal to wave front

Rays are not normal to wave front

Rays are normal to wave front

There is no relationship between rays and wave fronts

22. The diameter of a lens is called

Principal axis

Aperture

Focal length

Radius of curvature

23. Optic fibers are related with

Computer

None of these

Light

Communication

24. A lens which converges a beam of parallel rays to a point is called

Plano convex lens

Plano concave lens

Converging (or convex) lens

Diverging (or concave) lens

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

25l

16l

Page 2 of 6

26. In a compound microscope, the intermediate image is

Virtual, erect and magnified

Real, erect and magnified

Virtual, erect and reduced

Virtual, inverted and magnified

27. The fringe spacing in case of blue light

Increases

None of these

Remains the same

Decrease

28. Inverse square law for luminance is valid for

Isotropic point source

Cylindrical source

All types of sources

Search light

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

Y = (m+1/2)λL/d

Y = (m+1/2) dL/λ

Y = (m+1/2)λd/L

Y = (m+1)λL/d

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

Band emission spectrum

Line absorption spectrum

Band absorption spectrum

Line emission spectrum

31. The direction of a ray of light is _________ to the wave front.

Parallel

Opposite

Equal

Perpendicular

32. To get the position of the image of an object at least how many rays emerging from any point of the object are required?

33. A convex lens gives a virtual image only when the objects lies

Between principal focus and center of curvature

At the principal focus

Beyond 2 f

Between principal focus and optical center

34. The inability of the lens to focus all the dispersed colors at one point is called

All of the above

Chromatic aberration

Spherical aberration

Chromatic aberration as well as spherical aberration

35. The revolving power of a lens is given by

αmin = 1.21 λ/D

αmin = 1.22 λ/D

αmin = 1.22 D/λ

αmin = 1.28 D/λ

36. A beam of light enters air from water. Which of the following characteristics of light will not change in water?

Wavelength

Velocity

Amplitude

Frequency

37. Which part of the spectrum is most visible?

Yellow-green

Yellow

Violet

Red

38. The resolving power of telescope depends on

Length of the telescope

Focal length of eye lens

Diameter of the objective lens

Focal length of objective lens

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

Reflection

Diffraction

Interference

Refraction

40. On a rainy day, if there is an oil drop on tar road, colored rings are seen around this drop. This is because of

Diffraction pattern

Polarization

Interference pattern produced due to thin oil film

Total internal reflection of light

41. The velocity of light in vacuum can be changed by changing

Frequency

Amplitude

Wavelength

None of these

42. If the magnification M₁ = 20.0 for objective and M₂ = 12.0 then total magnification is

280

200

260

240

43. The separation between successive fringes in a double slit arrangement is x. If the whole arrangement is dipped under water what will be the new fringe separation? [The wavelength of light being used is 5000 A]

1.5 x

0.83x

44. The diameter of a lens under use is called the

Radius of curvature of the lens

Pole of the lens

Aperture of the lens

Principal focus of the lens

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

Increasing gradually

It is constant at the center

Decreasing gradually

None of these

46. Choose the correct statement

Rays are not normal to wave front

Rays may be normal to wave front

There is no relationship between rays and wave fronts

Rays are normal to wave front

47. Which one type of fiber is more suitable for transmission of signals in which white light is used?

Mono mode step index fiber

Multi-mode graded index fiber

Multi-mode step index fiber

Single mode step index fiber

48. A point where the incident parallel rays of light converge or appear to diverge after passing through a lens is called

Center of curvature

Aperture

Focus

Optical center

49. A convex lens has focal length F. An object is placed at F then

Image is formed at - ∞ and is real

Image is formed at - ∞ and is virtual

Image is formed at + ∞ and is real

Image is formed at + ∞ and is virtual

50. Finger prints on paper are identified by sprinkling fluorescent powder on it and observing it under

Infrared

Sun light

Sodium light

Page 3 of 6

51. A telescope has an objective lens of focal length 1.5m and an eye piece of focal length 5 cm. IF this telescope is used in normal setting to view a tower of height 100m located 3km away, what will be the height of the image of the tower?

25 cm

20 cm

10 cm

15 cm

52. Which does not show polarization?

Longitudinal waves in gas

None of these

Transverse wave in gas

Both A and B

53. Which of the following frequency ranges includes most of the electromagnetic waves emitted by the ultra – violet tubes used in a sun bed?

5 x 10¹⁴ to 5 x 10¹⁷ Hz

5 x 10⁵ to 5 x 10⁸ Hz

5 x 10¹¹ to 5 x 10¹⁴ Hz

5 x 10⁸ to 5 x 10¹¹ Hz

54. There is no noticeable boundary between core and cladding

Multi-mode step index fiber

All types of fiber

Single mode step index fiber

Multi-mode graded index fiber

55. Which of the following features determines the resolving power of telescope?

The focal length of eyepiece

The focal length of the objective

The diameter of the objective

Two of the above

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

d sin θ = (m + 1/2)

d sin θ = (m + 1/2)²

d sin θ = (m + 1)²

d sin θ = (m + 1/2)⁴

57. The astronomical telescope consists of objective and eye piece. The focal length of the objective is

Equal to that of the eye piece

Five times shorter than that of eye piece

Greater than that of eye piece

Shorter than that of eye piece

58. A polarizer is used to

Produce polarized light

Produce unpolarised light

Increase intensity of light

Reduced intensity of light

59. In astronomical telescope the final image for normal vision is formed at

The focus of the objective lens

The least distance of the distinct vision

The focal of the eye piece

Infinity

60. For constructive interference the path difference is

m²λ

mλ

½ mλ

(m – 1) λ

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

Emission spectrum

All of these

Line spectrum

Continuous emission spectrum

62. What is the main cayuse of the shining of diamond?

Total internal reflection

Refraction

Dispersion of light

Reflection

63. The power of a concave lens is

Positive

Virtual

Negative

Real

64. In compound microscope, length of microscope is 21.5 cm, focal length of objective is 1.6 cm, focal length of eye piece is 2.1 cm and if final image is formed at infinity they distance of object from objective lens is

6 cm

1.9 cm

4.8 cm

3 cm

65. If f = 5 cm and d = 25 cm then the magnification will be

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

Intensity ratio of the sources

Wavelength

Fringe width

Distance between the slits

67. Wavelength of light of frequency 100 Hz is

2 x 10⁶ m

3 x 10⁶ m

4 x 10⁶ m

5 x 10⁶ m

68. Geometrical optics cannot give following characteristics for a microscope

Resolution of image

Any of the above

Image position

Image size

69. A convex lens acts as a diverging lens if the

Both b and c

If the object is with in C

If the object is within f

Object is beyond C

70. Soap bubble looks colored due to

Dispersion

Reflection

Any one of these

Interference

71. If N is the number of rulings on the grating, then the resolving power in the mth order diffraction equals to

R = N x m

R = m/N

R = N x m²

R = N/m

72. In Newton’s rigs the point of contact of the lens and the glass plate, the air film is

Maximum

Zero

Minimum

None of these

73. Which of the following wavelengths will suffer maximum deviation while passing through a prism?

Violet

Red

Green

Orange

74. In a simple microscope lens used is _________.

Plano convex

Cylindrical

Biconcave

Biconvex

75. 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?

Decreasing the distance between the screen and the slits

Using monochromatic light of longer wavelength

Using monochromatic light of higher frequency

Increasing the distance between the slits

Page 4 of 6

76. Which is having minimum wavelength?

ϒ-rays

Ultra-violet rays

X-rays

Cosmic-rays

77. When at some angle of incidence, the angle of reflection is equal to 90°. This angle is called

Incidence angle

Critical angle

Deviation angle

Refractive angle

78. In optic fiber transmission system ________ are used regenerate the dim light signal.

Repeaters

Laser

Transformer

Diodes

79. In Young’s double slit experiment, the separation between the slits is made 3 fold, the fringe width becomes

9 times

3 times

1/3 times

1/9 times

80. Resolving power of a telescope depends on:

The magnification of eyepiece

Refractive index of objective lens

The focal length of objective lens

Diameter of objective lens

81. Which of the following is a part of spectrometer?

All of these

Collimator

Telescope

Turn table

82. Sun has elliptical shape, when it rises and sets due to

Reflection

Scattering

Refraction

Dispersion

83. When the object is placed at 2f of a convex lens then the image formed behind the lens will be

Beyond 2f

Between f and 2 f

At the focus

At 2f

84. A ________ lens is used to form Newton’s rings:

Plano-convex

Convexo-concave

Plano-concave

Double-convex

85. Which of the following spectrum have all the frequencies from high to low frequency range?

Continuous spectrum

Line spectrum

Band spectrum

Discontinuous spectrum

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

Monochromatic

Incoherent

Electromagnetic

In the form of a narrow beam

87. The length of a microscope is 12 cm and its magnifying power is 25 for relaxed eye. The focal length of the eye piece is 4 cm. The distance of the object from the objective is

2.5 cm

3 cm

3.5 cm

2 cm

88. The critical angle for a ray of light suffering total internal reflection will be smallest for the ray traveling from

Water to air

Glass to air

Water to glass

Glass to water

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

Monochromatic

Incoherent

In the form of a narrow beam

Electromagnetic

90. Magnification of the astronomical telescope is

fo/fe

(1+fo/fe)L/fo

fo+fe

fe/fo

91. Signal form a remote control to the device operated by it travels with the speed of:

Light

Sound

Supersonics

Ultrasonics

92. Final image produced by a compound microscope is

Real and erect

Virtual and erect

Virtual and inverted

Real and inverted

93. Magnifying power of simple microscope

List distance of distinct vision

Increase with increase in focal length

No effect with decrease or increase with focal length

Increase with decrease in focal length

94. Resolving power of a telescope depends on:

The focal length of objective lens

The magnification of eyepiece

Refractive index of objective lens

Diameter of objective lens

95. The difference between 1st ring fringe and 1st dark fringe is measured as

2λD/d

λD/4d

λD/d

λD/2d

96. Power of a lens is one diopter if its focal length is

2 meters

1 meter

4 meters

3 meters

97. For interference to occur, the two light waves should be:

Monochromatic

Of two different frequencies

Coming from opposite direction

Of high intensity

98. A spectrometer is an optical device used to study the spectra from different sources of light which is

fₑ + fₒ

fₒ - fₑ

None of these

fₑ - fₒ

99. Unit of power of a lens is

Watt

Horsepower

Meter

Diopter

100. The apparent size of an object depends on the angle subtended but it at the eye. As the angle increases the size of the object

None of these

Larger

Infinite

Smaller

Page 5 of 6

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

Diffraction

Refraction

Reflection

Origin of spectra

102. An object is placed between f and 2f of a concave lens. The image formed will formed will be

Real and Erect

Virtual and inverted

Virtual and Erect

Real and inverted

103. 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:

λ = dm

λ = 2d/m

2λ = dm

λ = 2π dm

104. The critical angle for a ray of light suffering total internal reflection will be smallest for the ray traveling from

Water to glass

Glass to water

Water to air

Glass to air

105. Near and far points of a healthy human eye respectively are

25 cm and infinity

25 cm and 100 cm

0 and infinity

0 and 25 cm

106. Wavelength of light of frequency 100 Hz is

3 x 10⁶ m

2 x 10⁶ m

5 x 10⁶ m

4 x 10⁶ m

107. For destructive interference, the path difference is give by:

(m – 1/2)λ

mλ

½ mλ

(m + 1/2)λ

108. In a astronomical telescope the final image for normal vision is formed at

The focus of the objective lens

Infinity

The focal of the eye piece

The least distance of the distinct vision

109. The focal lengths of the eye piece and objective of a telescope are respectively 100 cm and 2 cm. The moon subtends an angle of 0.5° at the eye. If it is looked through the telescope, the angle subtended by the moon’s image will be

50°

100°

10°

25°

110. Which of the following has least wavelength?

X-rays

ϒ-rays

Ultra-violet rays

Cosmic-rays

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

Line spectrum

Continuous emission spectrum

All of these

Emission spectrum

112. The cause of mirage observed in desert is

Scattering

Refraction

Reflection

Total internal reflection

113. At what distance should a book be placed from a 50 cd bulb so that the luminance on the book becomes 2 lm m¯²

50 m

1 m

10 m

5 m

114. For obtaining equal and same height of the image, mirror used should be

None

Plane

Convex

Concave

115. The speed of light in vacuum is 3 x 10⁵ ms¯¹. Its speed in a medium of refractive index 1.5 will be

2 x 10⁵ ms¯¹

5.5 x 10⁵

4.5 x 10⁸ cm

6.5 x 10⁸

116. If the distance of a surface from light source is doubled, then the luminance will become

4 times

½ times

¼ times

2 times

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

Diffraction

Interference

Refraction

Reflection

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

Of the same frequency and having definite phase relationship

Of nearly the same frequency

Different wavelength

Of same frequency

119. While viewing a distant object with a telescope suddenly a housefly sits on objective lens. The correct statement is that

Housefly will be seen reduced in image

Intensity of image will be decreased

Housefly will be seen enlarged in image

Intensity of image will be increased

120. If an object is placed away from 2f of a converging lens then the image will be

Virtual and erect

Real and inverted

Real and erect

Virtual

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

Speed of propagation of the wave

Speed of propagation less than the wave

None of these

Speed of propagation greater than wave

122. The resolving power of a telescope depends on

Its magnification

The ratio of the focal length and the diameter

Its diameter (of the objective)

Its focal length

123. If the red light is replaced by blue light illuminating the object in a microscope the resolving power of the microscope

Gets halved

Decreases

Remains unchanged

Increases

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

Do not affect a photographic plate

Cannot be polarized

Cannot be diffracted

Have a lower frequency

125. Image of an object 5 mm high is only 1 cm high, Magnification produced by lens is

0.5

0.2

Page 6 of 6

126. The electrical signals change into light signals for transmission through optical fiber. A light pulse represent

Zero (0)

One (1)

Neither zero (0) nor one (1)

Both zero (0) and one (1)

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

Laser rays are not absorbed

Laser rays are high velocity waves

Laser rays are most coherent waves

Laser rays propagate in a straight line

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

.d Sin θ = (m + ½)λ

½ d Sin θ = mλ

2π Sin θ = (m + ½)λ

.m Sin θ = (d + ½)λ

129. Consider telecommunication through optical fibers. Which of the following statements is not true?

Optical fibers can be of graded refractive index

Optical fibers have extremely low transmission loss

Optical fibers may have homogeneous core with a suitable cladding

Optical fibers are subject to electromagnetic interference from outside

130. While viewing a distant object with a telescope suddenly a housefly sits on objective lens. The correct statement is that

Intensity of image will be increased

Housefly will be seen enlarged in image

Housefly will be seen reduced in image

Intensity of image will be decreased

131. Inverse square law for luminance is valid for

All types of sources

Cylindrical source

Isotropic point source

Search light

132. What is the most important function of telescope?

None of these

Magnification

Resolution

Light collection

133. In a compound microscope, the intermediate image is

Virtual, erect and reduced

Virtual, inverted and magnified

Virtual, erect and magnified

Real, erect and magnified

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

Doppler’s effect

None of these

Diffraction

Interference

135. In the phenomenon of interference, the bright and dark fringes are of

Different width

Equal width

None of these

Dark fringes are thicker than bright

Police

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

Band absorption spectrum

Band emission spectrum

Line absorption spectrum

Line emission spectrum

You Can Learn and Gain more Knowledge through our Online Quiz and Testing system Just Search your desired Preparation subject at Gotest.

UET Peshawar Entry Test 2025 Registration Online ETEA Test D...
ECAT Statistics Test Set 17
ECAT Statistics Test Set 16
ECAT Statistics Test Set 15
ECAT Statistics Test Set 14
ECAT Statistics Test Set 13
ECAT Statistics Test Set 12
ECAT Statistics Test Set 11
ECAT Statistics Test Set 10
ECAT Statistics Test Set 9

Mustansar KhanLast Updated: April 18, 2025

Facebook Twitter Reddit WhatsApp Share via Email Print

ECAT Physics Optics Chapter Test Online

Physics Optics Chapter MCQS Online Test

ECAT Physics Electronics Chapter Online Test

ECAT Physics Optics Chapter Online Test

Physics

Police

You Might Also Like

Mustansar Khan

Leave a Reply Cancel reply

Physics Optics Chapter MCQS Online Test

ECAT Physics Electronics Chapter Online Test

ECAT Physics Optics Chapter Online Test

Physics

Police

You Might Also Like

Mustansar Khan

Your Related

ECAT Physics Of Solids Online Test

ECAT English Vocabulary 7 Test Online

ECAT Physics Force and motion Online Test

ECAT Computer Science Word Processing Test Online

ECAT Chemistry Forms of Matter Test Online

ECAT Computer Input Output Test Online

Leave a Reply Cancel reply