Light Part 4: MCQs (Q76–Q100)
💡 Light – MCQs for Class 8 Science
Part 4: Q76–Q100
Q76. The principle of the periscope is based on:
A) Refraction of light
B) Reflection of light
C) Dispersion of light
D) Scattering of light
✅ Correct Answer: B) Reflection of light
Explanation:
- B) ✔ Periscope uses plane mirrors at 45° for reflection.
Q77. Which part of the human eye helps to focus objects at different distances?
A) Iris
B) Retina
C) Cornea
D) Ciliary muscles
✅ Correct Answer: D) Ciliary muscles
Explanation:
- D) ✔ They adjust lens curvature to change focal length.
Q78. Which type of image can be formed by a concave mirror?
A) Only real
B) Only virtual
C) Both real and virtual
D) Neither
✅ Correct Answer: C) Both real and virtual
Explanation:
- C) ✔ Concave mirrors form real images beyond focus, virtual images within focus.
Q79. Which lens always forms a virtual, erect, and diminished image?
A) Convex lens
B) Concave lens
C) Cylindrical lens
D) Plano-convex lens
✅ Correct Answer: B) Concave lens
Explanation:
- B) ✔ Concave lens always gives diminished virtual images.
Q80. What is the nature of the image formed by a convex lens if the object is placed at infinity?
A) Virtual and erect
B) Real, inverted, and highly diminished
C) Real and same size
D) Virtual and magnified
✅ Correct Answer: B) Real, inverted, and highly diminished
Explanation:
- B) ✔ Parallel rays converge at focus → tiny inverted image.
Q81. Which part of the eye acts like a natural convex lens?
A) Retina
B) Cornea
C) Eye lens
D) Iris
✅ Correct Answer: C) Eye lens
Explanation:
- C) ✔ Eye lens refracts and focuses light on retina.
Q82. The ability of the eye to focus on objects at different distances is called:
A) Refraction
B) Persistence of vision
C) Accommodation
D) Dispersion
✅ Correct Answer: C) Accommodation
Explanation:
- C) ✔ Adjustment of focal length by ciliary muscles = accommodation.
Q83. The image formed by convex mirrors is always:
A) Virtual, erect, diminished
B) Real, inverted, enlarged
C) Virtual, erect, magnified
D) Real and diminished
✅ Correct Answer: A) Virtual, erect, diminished
Explanation:
- A) ✔ Convex mirrors always form diminished upright images.
Q84. The medical condition where near objects are blurred due to short eyeball is:
A) Myopia
B) Hypermetropia
C) Cataract
D) Presbyopia
✅ Correct Answer: B) Hypermetropia
Explanation:
- B) ✔ Short eyeball → image formed behind retina.
Q85. The medical condition where distant objects are blurred due to long eyeball is:
A) Myopia
B) Hypermetropia
C) Presbyopia
D) Cataract
✅ Correct Answer: A) Myopia
Explanation:
- A) ✔ Long eyeball → image forms before retina.
Q86. Which type of lens is used to correct presbyopia?
A) Bifocal lenses
B) Concave lens
C) Convex lens
D) Cylindrical lens
✅ Correct Answer: A) Bifocal lenses
Explanation:
- A) ✔ Combine convex (near) and concave (distant) lenses.
Q87. Which part of the human eye controls the size of the pupil?
A) Retina
B) Iris
C) Cornea
D) Lens
✅ Correct Answer: B) Iris
Explanation:
- B) ✔ Iris muscles contract or relax → adjust pupil size.
Q88. The device that uses a convex lens to produce magnified images of small objects is:
A) Telescope
B) Microscope
C) Periscope
D) Kaleidoscope
✅ Correct Answer: B) Microscope
Explanation:
- B) ✔ Convex lenses magnify tiny objects in a microscope.
Q89. Which of the following is NOT due to refraction of light?
A) Twinkling of stars
B) Rainbow formation
C) Bending of pencil in water
D) Reflection in mirror
✅ Correct Answer: D) Reflection in mirror
Explanation:
- D) ✔ Reflection is bouncing back, not bending.
Q90. The rear-view mirrors in vehicles are made of:
A) Concave mirrors
B) Plane mirrors
C) Convex mirrors
D) Combination mirrors
✅ Correct Answer: C) Convex mirrors
Explanation:
- C) ✔ Convex mirrors give a wide field of view.
Q91. Which phenomenon causes a coin at the bottom of a glass of water to appear raised?
A) Reflection
B) Refraction
C) Dispersion
D) Scattering
✅ Correct Answer: B) Refraction
Explanation:
- B) ✔ Light bends as it leaves water → coin looks raised.
Q92. Which of these devices uses total internal reflection?
A) Kaleidoscope
B) Periscope
C) Optical fibre
D) Microscope
✅ Correct Answer: C) Optical fibre
Explanation:
- C) ✔ Optical fibres use TIR to transmit light signals.
Q93. The eye defect corrected using cylindrical lenses is:
A) Presbyopia
B) Astigmatism
C) Myopia
D) Hypermetropia
✅ Correct Answer: B) Astigmatism
Explanation:
- B) ✔ Uneven cornea curvature corrected by cylindrical lenses.
Q94. A rainbow is an example of:
A) Reflection only
B) Refraction, dispersion, and internal reflection
C) Diffraction
D) Scattering only
✅ Correct Answer: B) Refraction, dispersion, and internal reflection
Explanation:
- B) ✔ All three phenomena occur inside water droplets.
Q95. Which lens is used in projectors to obtain a real, inverted, and magnified image?
A) Convex lens
B) Concave lens
C) Cylindrical lens
D) Plane mirror
✅ Correct Answer: A) Convex lens
Explanation:
- A) ✔ Convex lens converges light to form real magnified images on screen.
Q96. Which type of image is formed on the retina of the human eye?
A) Real and inverted
B) Real and erect
C) Virtual and inverted
D) Virtual and erect
✅ Correct Answer: A) Real and inverted
Explanation:
- A) ✔ Natural eye lens produces real inverted image.
Q97. The splitting of white light into seven colours by a prism is due to:
A) Equal bending of light
B) Dispersion
C) Reflection
D) Scattering
✅ Correct Answer: B) Dispersion
Explanation:
- B) ✔ Different colours bend differently in prism.
Q98. Which colour of light is scattered the most in the atmosphere?
A) Red
B) Yellow
C) Blue
D) Green
✅ Correct Answer: C) Blue
Explanation:
- C) ✔ Blue light has shorter wavelength → scattered most → sky looks blue.
Q99. Which phenomenon explains why the sun appears reddish at sunrise and sunset?
A) Reflection
B) Refraction
C) Scattering
D) Dispersion
✅ Correct Answer: C) Scattering
Explanation:
- C) ✔ Longer path → blue light scattered away → red light reaches eyes.
Q100. The principle behind the working of kaleidoscope is:
A) Refraction
B) Multiple reflections
C) Dispersion
D) Total internal reflection
✅ Correct Answer: B) Multiple reflections
Explanation:
- B) ✔ Mirrors placed at angles produce symmetrical patterns by reflection.
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