Human Eye and Colourful World Part 1: MCQs (Q1–Q25)
📘 Human Eye and Colourful World – MCQs (Class 10 Science)
🔹 Part 1: Questions 1–25
Q1. The front transparent part of the eye is called:
A) Retina
B) Iris
C) Cornea
D) Lens
Correct Answer: C) Cornea
Explanation:
- A) Retina → Inner screen where image forms.
- B) Iris → Controls pupil size, regulates light.
- ✅ C) Cornea → Transparent covering, refracts major light.
- D) Lens → Helps in focusing.
Q2. The coloured part of the eye that controls the size of the pupil is:
A) Lens
B) Retina
C) Iris
D) Cornea
Correct Answer: C) Iris
Explanation:
- A) Lens → Adjusts focus, not colour.
- B) Retina → Image formation.
- ✅ C) Iris → Coloured part, regulates pupil size.
- D) Cornea → Transparent covering.
Q3. The process by which the eye lens changes its focal length to focus objects at different distances is called:
A) Refraction
B) Accommodation
C) Persistence of vision
D) Dispersion
Correct Answer: B) Accommodation
Explanation:
- A) Refraction → Bending of light.
- ✅ B) Accommodation → Eye lens adjusts thickness for near/far objects.
- C) Persistence of vision → Image remains on retina briefly.
- D) Dispersion → Splitting of light.
Q4. The least distance of distinct vision for a normal eye is:
A) 10 cm
B) 25 cm
C) 50 cm
D) 100 cm
Correct Answer: B) 25 cm
Explanation:
- ✅ B) For normal human eye, near point = 25 cm.
- A, C, D → Incorrect values.
Q5. The farthest point up to which the eye can see objects clearly is called:
A) Far point
B) Near point
C) Blind spot
D) Principal focus
Correct Answer: A) Far point
Explanation:
- ✅ A) Far point = Infinity for normal eye.
- B) Near point = 25 cm.
- C) Blind spot = No image formation.
- D) Principal focus = Lens property, not eye.
Q6. The defect in which a person cannot see distant objects clearly is:
A) Hypermetropia
B) Myopia
C) Presbyopia
D) Astigmatism
Correct Answer: B) Myopia
Explanation:
- A) Hypermetropia → Problem in seeing nearby objects.
- ✅ B) Myopia (short-sightedness) → Near objects clear, far blurred.
- C) Presbyopia → Old-age defect.
- D) Astigmatism → Uneven curvature.
Q7. Myopia is corrected by using:
A) Convex lens
B) Concave lens
C) Cylindrical lens
D) Plano-convex lens
Correct Answer: B) Concave lens
Explanation:
- A) Convex → For hypermetropia.
- ✅ B) Concave → Diverging lens shifts image onto retina.
- C, D → Not used here.
Q8. Hypermetropia is corrected using:
A) Concave lens
B) Convex lens
C) Cylindrical lens
D) None
Correct Answer: B) Convex lens
Explanation:
- ✅ B) Convex → Converging lens helps focus near objects on retina.
- A) Concave → For myopia.
- C, D → Not applicable.
Q9. The old-age defect of the eye due to reduced flexibility of lens is:
A) Myopia
B) Hypermetropia
C) Presbyopia
D) Astigmatism
Correct Answer: C) Presbyopia
Explanation:
- A, B → Other vision defects.
- ✅ C) Presbyopia → Age-related, corrected by bifocals.
- D) Astigmatism → Due to uneven cornea curvature.
Q10. The splitting of white light into seven colours is called:
A) Reflection
B) Dispersion
C) Refraction
D) Scattering
Correct Answer: B) Dispersion
Explanation:
- ✅ B) Dispersion → Splitting due to different refractive indices.
- A, C, D → Other phenomena.
Q11. Which colour deviates the least during dispersion?
A) Red
B) Violet
C) Blue
D) Green
Correct Answer: A) Red
Explanation:
- ✅ A) Red → Longest wavelength, least deviation.
- B) Violet → Shortest wavelength, maximum deviation.
- C, D → Intermediate.
Q12. The band of seven colours obtained due to dispersion is called:
A) Halo
B) Spectrum
C) Shadow
D) Mirage
Correct Answer: B) Spectrum
Explanation:
- ✅ B) Spectrum = VIBGYOR colours.
- A, C, D → Different optical phenomena.
Q13. The rainbow in the sky is formed due to:
A) Refraction and reflection in raindrops
B) Only reflection
C) Only refraction
D) Dispersion in clouds
Correct Answer: A) Refraction and reflection in raindrops
Explanation:
- ✅ A) Refraction + internal reflection + dispersion → Rainbow formation.
- B, C, D → Partial/incomplete.
Q14. The blue colour of sky is due to:
A) Dispersion
B) Scattering of light
C) Refraction
D) Reflection
Correct Answer: B) Scattering of light
Explanation:
- ✅ B) Blue light (shorter wavelength) scattered more.
- A, C, D → Not main reason.
Q15. The danger signal lights are red because:
A) Red scatters the most
B) Red has shortest wavelength
C) Red has longest wavelength
D) Red cannot be seen at night
Correct Answer: C) Red has longest wavelength
Explanation:
- ✅ C) Red light least scattered, travels longest distance.
- A, B, D → Incorrect reasons.
Q16. The time difference between actual sunset and apparent sunset is about:
A) 1 minute
B) 2 minutes
C) 4 minutes
D) 8 minutes
Correct Answer: C) 4 minutes
Explanation:
- ✅ C) Atmospheric refraction delays sunset by ~2 min and advances sunrise by ~2 min → Total 4 minutes.
Q17. Twinkling of stars is due to:
A) Reflection of light
B) Refraction of light
C) Atmospheric refraction and variation in air density
D) Dispersion
Correct Answer: C) Atmospheric refraction and variation in air density
Explanation:
- ✅ C) Star light refracts randomly through air layers → Twinkling.
- A, B, D → Not complete reason.
Q18. Stars appear higher in the sky than actual position due to:
A) Reflection
B) Refraction of light in atmosphere
C) Dispersion
D) Scattering
Correct Answer: B) Refraction of light in atmosphere
Explanation:
- ✅ B) Light bends towards normal → Apparent shift upwards.
Q19. The phenomenon of advance sunrise and delayed sunset is due to:
A) Reflection
B) Refraction of sunlight by atmosphere
C) Dispersion
D) Scattering
Correct Answer: B) Refraction of sunlight by atmosphere
Explanation:
- ✅ B) Sun visible even when below horizon due to atmospheric refraction.
Q20. The eye lens is a:
A) Convex lens
B) Concave lens
C) Plane mirror
D) Concave mirror
Correct Answer: A) Convex lens
Explanation:
- ✅ A) Eye lens is biconvex, converges rays on retina.
Q21. The persistence of vision of human eye is about:
A) 1/10 s
B) 1/16 s
C) 1/20 s
D) 1/25 s
Correct Answer: B) 1/16 s
Explanation:
- ✅ B) Retinal image lasts ~1/16 s.
Q22. The white light of the Sun is composed of:
A) 5 colours
B) 6 colours
C) 7 colours
D) 9 colours
Correct Answer: C) 7 colours
Explanation:
- ✅ C) VIBGYOR (7 colours).
Q23. The scattering of light is inversely proportional to:
A) Wavelength²
B) Wavelength³
C) Wavelength⁴
D) Wavelength
Correct Answer: C) Wavelength⁴
Explanation:
- ✅ C) Rayleigh scattering ∝ 1/λ⁴.
- Blue scattered more than red.
Q24. The red colour of the Sun at sunrise and sunset is due to:
A) Dispersion
B) Scattering of shorter wavelengths away
C) Absorption of red light
D) Refraction
Correct Answer: B) Scattering of shorter wavelengths away
Explanation:
- ✅ B) Blue scattered out, red reaches observer.
Q25. The splitting of white light into colours by a prism shows:
A) Reflection of light
B) Dispersion of light
C) Refraction without bending
D) Diffraction of light
Correct Answer: B) Dispersion of light
Explanation:
- ✅ B) Different colours deviate differently, forming spectrum.
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