Human Eye and Colourful World Part 4: MCQs (Q76–Q100)
📘 Human Eye and Colourful World – MCQs (Class 10 Science)
🔹 Part 4: Questions 76–100
Q76. The human eye forms an image at:
A) Cornea
B) Lens
C) Retina
D) Iris
Correct Answer: C) Retina
Explanation:
- A) Cornea → Refracts light.
- B) Lens → Focuses light.
- ✅ C) Retina → Light-sensitive screen for image.
- D) Iris → Controls light entry.
Q77. The normal far point of a human eye is at:
A) 25 cm
B) 50 cm
C) 1 m
D) Infinity
Correct Answer: D) Infinity
Explanation:
- ✅ D) Normal eye → Sees distant objects (infinity) clearly.
Q78. The eye lens becomes thin when:
A) Ciliary muscles contract
B) Ciliary muscles relax
C) Pupil expands
D) Retina shifts
Correct Answer: B) Ciliary muscles relax
Explanation:
- ✅ B) Relaxation → Lens less curved → Longer focal length → For distant vision.
Q79. Which colour of white light has the longest wavelength?
A) Red
B) Violet
C) Blue
D) Yellow
Correct Answer: A) Red
Explanation:
- ✅ A) Red has ~700 nm → Longest λ, least deviation.
Q80. Which part of the eye controls the amount of light entering?
A) Cornea
B) Retina
C) Iris
D) Lens
Correct Answer: C) Iris
Explanation:
- ✅ C) Iris → Contracts/expands pupil.
Q81. The phenomenon of twinkling of stars is absent when seen from:
A) Earth’s surface
B) Airplane
C) Space
D) Mountain top
Correct Answer: C) Space
Explanation:
- ✅ C) No atmosphere → No refraction → No twinkling.
Q82. The blue colour of the sky is due to:
A) Reflection
B) Refraction
C) Scattering
D) Dispersion
Correct Answer: C) Scattering
Explanation:
- ✅ C) Rayleigh scattering → Blue light scattered more.
Q83. The sun appears reddish at sunrise because:
A) Atmosphere absorbs red
B) Blue light scattered away
C) Dispersion of light
D) Sun is cool
Correct Answer: B) Blue light scattered away
Explanation:
- ✅ B) Long path → Short λ scattered, only red reaches.
Q84. Which part of eye acts like camera film (screen)?
A) Cornea
B) Lens
C) Retina
D) Pupil
Correct Answer: C) Retina
Explanation:
- ✅ C) Retina → Screen of eye, captures image.
Q85. Which phenomenon explains the appearance of Sun 2 minutes before actual sunrise?
A) Dispersion
B) Refraction
C) Scattering
D) Diffraction
Correct Answer: B) Refraction
Explanation:
- ✅ B) Atmospheric refraction bends rays → Sun visible earlier.
Q86. In presbyopia, the person cannot:
A) See nearby objects clearly
B) See distant objects clearly
C) See colours
D) See in dark
Correct Answer: A) See nearby objects clearly
Explanation:
- ✅ A) Lens loses flexibility with age → Near point increases.
Q87. Myopia is corrected using:
A) Convex lens
B) Concave lens
C) Cylindrical lens
D) Bifocal lens
Correct Answer: B) Concave lens
Explanation:
- ✅ B) Concave → Diverging lens brings image onto retina.
Q88. Hypermetropia is corrected using:
A) Concave lens
B) Convex lens
C) Cylindrical lens
D) Plane mirror
Correct Answer: B) Convex lens
Explanation:
- ✅ B) Convex → Converging lens shifts near images to retina.
Q89. Which lens is used in spectacles of a person with presbyopia and myopia both?
A) Concave
B) Convex
C) Cylindrical
D) Bifocal
Correct Answer: D) Bifocal
Explanation:
- ✅ D) Bifocal → Upper part concave (for distant), lower convex (for near).
Q90. The least distance of distinct vision is also called:
A) Near point
B) Far point
C) Blind spot
D) Focal length
Correct Answer: A) Near point
Explanation:
- ✅ A) Near point = 25 cm for normal eye.
Q91. The focal length of a lens of power +2D is:
A) 25 cm
B) 50 cm
C) 100 cm
D) 200 cm
Correct Answer: B) 50 cm
Explanation:
- f = 100/P = 100/2 = 50 cm.
- ✅ B correct.
Q92. The power of a lens of focal length –100 cm is:
A) –0.5 D
B) –1 D
C) +1 D
D) +0.5 D
Correct Answer: B) –1 D
Explanation:
- P = 100/f = 100/–100 = –1 D.
- ✅ B correct.
Q93. Which of the following phenomena explains spectrum formation by a prism?
A) Dispersion
B) Reflection
C) Scattering
D) Diffraction
Correct Answer: A) Dispersion
Explanation:
- ✅ A) Different colours deviate differently → Spectrum.
Q94. Which of the following is responsible for “Mirage”?
A) Scattering
B) Atmospheric refraction and TIR
C) Dispersion
D) Diffraction
Correct Answer: B) Atmospheric refraction and TIR
Explanation:
- ✅ B) Hot air near ground → Light bends and undergoes TIR.
Q95. The rainbow is always formed in the direction:
A) Towards the Sun
B) Opposite to the Sun
C) At zenith
D) At horizon
Correct Answer: B) Opposite to the Sun
Explanation:
- ✅ B) Observer must face away from Sun to see rainbow.
Q96. The splitting of sunlight into spectrum is due to:
A) Same speed of colours in glass
B) Different speeds of colours in glass
C) Absorption of light by glass
D) Reflection inside glass
Correct Answer: B) Different speeds of colours in glass
Explanation:
- ✅ B) Different wavelengths refract differently.
Q97. The rods in retina are sensitive to:
A) Dim light
B) Bright light
C) Colour
D) None
Correct Answer: A) Dim light
Explanation:
- ✅ A) Rod cells → Dim light vision.
Q98. The cones in retina are responsible for:
A) Black & white vision
B) Colour vision
C) Night vision
D) Blind spot
Correct Answer: B) Colour vision
Explanation:
- ✅ B) Cone cells → Detect colours in bright light.
Q99. The part of the eye where no image is formed is:
A) Lens
B) Pupil
C) Blind spot
D) Retina
Correct Answer: C) Blind spot
Explanation:
- ✅ C) No rods or cones at optic nerve region.
Q100. Which of the following is NOT due to atmospheric refraction?
A) Apparent star position
B) Twinkling of stars
C) Blue colour of sky
D) Advance sunrise
Correct Answer: C) Blue colour of sky
Explanation:
- ✅ C) Blue sky → Scattering, not refraction.
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