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

Page 1 of 6

Physics

1. Choose the correct statement

Rays are not normal to wave front

Rays are normal to wave front

There is no relationship between rays and wave fronts

Rays may be normal to wave front

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

2 times

4 times

¼ times

½ times

3. 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

4. The diameter of a lens is called

Principal axis

Focal length

Radius of curvature

Aperture

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

Of nearly the same frequency

Of same frequency

Different wavelength

Of the same frequency and having definite phase relationship

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

Total internal reflection of light

Diffraction pattern

Polarization

Interference pattern produced due to thin oil film

7. 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?

15 cm

25 cm

10 cm

20 cm

8. Final image produced by a compound microscope is

Real and inverted

Real and erect

Virtual and erect

Virtual and inverted

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

Sun light

Infrared

Sodium light

10. 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

Smaller

Infinite

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

The focal of the eye piece

Infinity

The focus of the objective lens

The least distance of the distinct vision

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

Continuous spectrum

Line spectrum

Discontinuous spectrum

Band spectrum

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

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

Between principal focus and center of curvature

Between principal focus and optical center

Beyond 2 f

At the principal focus

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

Both zero (0) and one (1)

Zero (0)

One (1)

Neither zero (0) nor one (1)

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

Red

Blue

Green

Yellow

17. Soap bubble looks colored due to

Interference

Dispersion

Reflection

Any one of these

18. In a simple microscope lens used is _________.

Biconvex

Biconcave

Cylindrical

Plano convex

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

Multi-mode graded index fiber

Multi-mode step index fiber

Mono mode step index fiber

Single mode step index fiber

20. 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

21. For constructive interference the path difference is

(m – 1) λ

½ mλ

mλ

m²λ

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

Same

Different

Zero

Different with refractive index of core higher than cladding

23. Resolving power of a telescope depends on:

Refractive index of objective lens

The magnification of eyepiece

Diameter of objective lens

The focal length of objective lens

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

2/10 diopter

1/10 diopter

10 diopter

11 diopter

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

½ d Sin θ = mλ

.m Sin θ = (d + ½)λ

.d Sin θ = (m + ½)λ

2π Sin θ = (m + ½)λ

Page 2 of 6

26. Which is having minimum wavelength?

Ultra-violet rays

Cosmic-rays

ϒ-rays

X-rays

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

Virtual and Erect

Real and inverted

Virtual and inverted

Real and Erect

28. Which of the following has least wavelength?

Ultra-violet rays

X-rays

Cosmic-rays

ϒ-rays

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

25 cm and infinity

0 and 25 cm

0 and infinity

25 cm and 100 cm

30. The resolving power of a telescope depends on

Its diameter (of the objective)

Its magnification

The ratio of the focal length and the diameter

Its focal length

31. What is the most important function of telescope?

Magnification

None of these

Resolution

Light collection

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

½ mλ

mλ

(m + 1/2)λ

(m – 1/2)λ

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

Dispersion

Diffraction

Reflection

Refraction

34. 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

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

λD/4d

λD/2d

λD/d

2λD/d

36. 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

3 cm

4.8 cm

1.9 cm

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

9 times

1/3 times

1/9 times

3 times

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

Producer

Origin

Source

Base

39. 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

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

Interference

Diffraction

Doppler’s effect

None of these

41. There is no noticeable boundary between core and cladding

All types of fiber

Multi-mode step index fiber

Multi-mode graded index fiber

Single mode step index fiber

42. Ray optics is valid, when characteristic dimensions are

Much smaller than the wavelength of length

Much larger than the wavelength of light

Of the same order as the wavelength of light

Of the order of one millimeter

43. The revolving power of a lens is given by

αmin = 1.22 D/λ

αmin = 1.28 D/λ

αmin = 1.22 λ/D

αmin = 1.21 λ/D

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

d sin θ = (m + 1/2)

d sin θ = (m + 1)²

d sin θ = (m + 1/2)⁴

d sin θ = (m + 1/2)²

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

Y = (m+1/2)λL/d

Y = (m+1/2)λd/L

Y = (m+1)λL/d

Y = (m+1/2) dL/λ

46. 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

Doubled

Unchanged

Halved

Quadrupled

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

Emission spectrum

Continuous emission spectrum

All of these

Line spectrum

48. 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

Intensity of image will be decreased

Housefly will be seen reduced in image

49. Optic fibers are related with

Light

Computer

Communication

None of these

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

Water to air

Water to glass

Glass to water

Glass to air

Page 3 of 6

51. The cause of mirage observed in desert is

Total internal reflection

Refraction

Reflection

Scattering

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

Momentum

Intensity

Amplitude

Energy

53. 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 real

Image is formed at + ∞ and is virtual

Image is formed at - ∞ and is virtual

54. Unit of power of a lens is

Horsepower

Meter

Watt

Diopter

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

None of these

Speed of propagation less than the wave

Speed of propagation of the wave

Speed of propagation greater than wave

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

None of these

Zero

Minimum

Maximum

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

Plano concave lens

Plano convex lens

Diverging (or concave) lens

Converging (or convex) lens

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

All of the above

Chromatic aberration as well as spherical aberration

Chromatic aberration

Spherical aberration

59. The setting of Newton’s rings is

None of these

A Plano convex lens and simple glass sheet

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

A Plano convex lens and the plane glass plate

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

Optical fibers are subject to electromagnetic interference from outside

Optical fibers may have homogeneous core with a suitable cladding

Optical fibers have extremely low transmission loss

Optical fibers can be of graded refractive index

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

Plano-convex

Convexo-concave

Plano-concave

Double-convex

62. Choose the correct statement

Raya may be normal to wave front

There is no relationship between rays and wave fronts

Rays are normal to wave front

Rays are not normal to wave front

63. Resolving power of a telescope depends on:

Refractive index of objective lens

The focal length of objective lens

Diameter of objective lens

The magnification of eyepiece

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

Sound

Ultrasonics

Light

Supersonics

65. The fringe spacing in case of blue light

None of these

Increases

Remains the same

Decrease

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

2 meters

3 meters

4 meters

1 meter

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

Laser rays are not absorbed

Laser rays are high velocity waves

Laser rays propagate in a straight line

Laser rays are most coherent waves

68. Wavelength of light of frequency 100 Hz is

2 x 10⁶ m

5 x 10⁶ m

3 x 10⁶ m

4 x 10⁶ m

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

Energy of different colors is different

Amplitude of different colors is different

Phase of different colors is different

Velocity of different colors is different

70. Inverse square law for luminance is valid for

Search light

All types of sources

Isotropic point source

Cylindrical source

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

Refraction

Interference

Reflection

Diffraction

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

The focal length of eyepiece

Two of the above

The diameter of the objective

The focal length of the objective

73. Which does not show polarization?

Both A and B

Longitudinal waves in gas

None of these

Transverse wave in gas

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

Dispersion of light

Total internal reflection

Refraction

Reflection

75. Geometrical optics cannot give following characteristics for a microscope

Image size

Resolution of image

Image position

Any of the above

Page 4 of 6

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

Virtual

Real and erect

Real and inverted

Virtual and erect

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

Diffraction

Refraction

Reflection

Interference

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

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

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

Housefly will be seen enlarged in image

Intensity of image will be increased

Housefly will be seen reduced in image

Intensity of image will be decreased

81. The power of a concave lens is

Real

Negative

Virtual

Positive

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

Continuous emission spectrum

Line spectrum

All of these

Emission spectrum

83. 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 10¹¹ to 5 x 10¹⁴ Hz

5 x 10¹⁴ to 5 x 10¹⁷ Hz

5 x 10⁸ to 5 x 10¹¹ Hz

5 x 10⁵ to 5 x 10⁸ Hz

84. 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

3.5 cm

2 cm

2.5 cm

3 cm

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

Incidence angle

Deviation angle

Refractive angle

Critical angle

86. Geometrical optics cannot give following characteristics for a microscope

Image size

Resolution of image

Any of the above

Image position

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

5.5 x 10⁵

2 x 10⁵ ms¯¹

6.5 x 10⁸

4.5 x 10⁸ cm

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

Turn table

All of these

Telescope

Collimator

89. In a compound microscope, the intermediate image is

Virtual, erect and magnified

Virtual, erect and reduced

Virtual, inverted and magnified

Real, erect and magnified

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

Of high intensity

Coming from opposite direction

Of two different frequencies

Monochromatic

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

Dark fringes are thicker than bright

Equal width

None of these

Different width

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

Equal

Opposite

Perpendicular

Parallel

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

Laser

Diodes

Transformer

Repeaters

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

0.2

0.5

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

The least distance of the distinct vision

The focal of the eye piece

The focus of the objective lens

Infinity

96. A polarizer is used to

Produce polarized light

Produce unpolarised light

Reduced intensity of light

Increase intensity of light

97. 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]

0.83x

1.5 x

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

260

240

280

200

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

All of these

Between f and 2f

Inside the focus

At the focus

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

At the focus

Between f and 2 f

At 2f

Beyond 2f

Page 5 of 6

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

White light

Coherent

Of difference frequencies

Added

102. The cause of mirage observed in desert is

Reflection

Scattering

Total internal reflection

Refraction

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

Origin of spectra

Reflection

Diffraction

Refraction

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

Do not affect a photographic plate

Have a lower frequency

Cannot be diffracted

Cannot be polarized

105. The resolving power of telescope depends on

Focal length of objective lens

Length of the telescope

Focal length of eye lens

Diameter of the objective lens

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

Concave

Convex

None

Plane

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

In the form of a narrow beam

Monochromatic

Incoherent

Electromagnetic

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

In the form of a narrow beam

Incoherent

Electromagnetic

Monochromatic

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

Scattering

Refraction

Dispersion

Reflection

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

Intensity ratio of the sources

Fringe width

Distance between the slits

Wavelength

111. Wavelength of light of frequency 100 Hz is

3 x 10⁶ m

2 x 10⁶ m

4 x 10⁶ m

5 x 10⁶ m

112. Magnification of the astronomical telescope is

(1+fo/fe)L/fo

fo/fe

fo+fe

fe/fo

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

Elliptical

Parabolic

Straight

Circular

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

Plane

None

Convex

Concave

115. Inverse square law for luminance is valid for

Search light

Cylindrical source

Isotropic point source

All types of sources

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

If the object is within f

Object is beyond C

Both b and c

If the object is with in C

117. Magnifying power of simple microscope

No effect with decrease or increase with focal length

List distance of distinct vision

Increase with increase in focal length

Increase with decrease in focal length

118. 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?

Increasing the distance between the slits

Using monochromatic light of higher frequency

Decreasing the distance between the screen and the slits

Using monochromatic light of longer wavelength

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

25l

16l

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

Focus

Optical center

Aperture

Center of curvature

121. 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

25°

10°

50°

100°

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

Red

Green

Violet

Orange

123. For the normal setting of a telescope

Only the final image is at infinity

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

Only the object is at infinity

Both the object and the final image is at infinity

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

Remains unchanged

Gets halved

Decreases

Increases

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

Amplitude

Velocity

Wavelength

Frequency

Page 6 of 6

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

R = N x m²

R = m/N

R = N/m

R = N x m

127. 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

10 m

50 m

1 m

5 m

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

Laser rays propagate in a straight line

Laser rays are high velocity waves

Laser rays are not absorbed

Laser rays are most coherent waves

129. In a compound microscope, the intermediate image is

Virtual, inverted and magnified

Virtual, erect and magnified

Real, erect and magnified

Virtual, erect and reduced

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

Wavelength

None of these

Frequency

Amplitude

131. Which part of the spectrum is most visible?

Violet

Red

Yellow

Yellow-green

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

Line absorption spectrum

Band absorption spectrum

Band emission spectrum

Line emission spectrum

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

Pole of the lens

Radius of curvature of the lens

Principal focus of the lens

Aperture of the lens

134. 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 = 2π dm

2λ = dm

λ = 2d/m

λ = dm

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

It is constant at the center

Decreasing gradually

None of these

Increasing gradually

Police

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

Line emission spectrum

Band absorption spectrum

Band emission spectrum

Line absorption spectrum

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

ECAT Chemistry Environmental Chemistry Test Online
ECAT Chemistry Common Chemical Industries in Pakistan Test O...
ECAT Chemistry Macro-Molecules Test Online
ECAT Chemistry Carboxylic Acid Test Online
ECAT Chemistry Aldehydes and Ketones Test Online
ECAT Chemistry Alcohols Phenols And Ethers Test Online
ECAT Chemistry Alkyl Halides Test Online
ECAT Chemistry Aromatic Hydrocarbons Test Online
ECAT Chemistry Aliphatic Hydrocarbons Test Online
ECAT Chemistry Fundamental Principles of Organic Chemistry T...

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 Mathematics Number System Test Online

Mehran University Sindh ECAT Maths Entry Test Online Preparation

UET Peshawar ECAT Computer Science Entry Test Online Preparation

ECAT Mathematics Fundamentals of Trigonometry Online Test

ECAT English Correction Test Online

ECAT Chemistry Aromatic Hydrocarbons Test Online

Leave a Reply Cancel reply