The Human Eye and the Colourful World — Class 10 MCQs with Answers

The Human Eye and the Colourful World — important questions & MCQs with answers (Class 10 Science (Physics))

6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.

0 of 6 answered

1. Q1 of 6Easy

   Image in human eye is formed on:

   ARetinaBIrisCCorneaDPupil
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   Answer: Retina

   Explanation: The retina is the light-sensitive screen at the back of the eye where the lens forms a real, inverted image, just as film does in a camera; the cornea and iris sit near the front and never carry the image.

2. Q2 of 6Easy

   The lens of the human eye is:

   AConvexBConcaveCPlaneDCylindrical
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   Answer: Convex

   Explanation: The eye lens is a convex (biconvex), transparent, flexible structure that converges light rays onto the retina; its curvature is what the ciliary muscles adjust during accommodation.

3. Q3 of 6Medium

   The ability of the eye lens to adjust its focal length is called its:

   APower of resolutionBPower of accommodationCRefractive indexDLeast distance of vision
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   Answer: Power of accommodation

   Explanation: The ability of the eye lens to adjust its focal length so as to focus objects at different distances is called the power of accommodation.

4. Q4 of 6Medium

   Assertion (A): Danger signal lights are red in colour. Reason (R): Red light is scattered the most by fog or smoke.

   ABoth A and R are true and R is the correct explanation of ABBoth A and R are true but R is not the correct explanation of ACA is true but R is falseDA is false but R is true
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   Answer: A is true but R is false

   Explanation: A is true. R is false: red light is scattered the least by fog or smoke, which is why it can be seen in the same colour from a distance.

5. Q5 of 6Hard

   White light passing through a prism shows that white light is:

   AOnly violetBA pure colourCOnly redDA mixture of seven colours
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   Answer: A mixture of seven colours

   Explanation: A prism splits white light into the seven colours (VIBGYOR), showing white light is a mixture of colours — Newton's classic experiment.

6. Q6 of 6Hard

   Assertion (A): A star seen near the horizon appears slightly higher than its actual position. Reason (R): Starlight passing through the atmosphere, whose refractive index changes gradually, is bent towards the normal.

   ABoth A and R are true and R is the correct explanation of ABBoth A and R are true but R is not the correct explanation of ACA is true but R is falseDA is false but R is true
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   Answer: Both A and R are true and R is the correct explanation of A

   Explanation: Both are true. Because the atmosphere bends starlight towards the normal, the star's apparent position is shifted, and near the horizon it looks higher than it really is.

The Human Eye and the Colourful World notes: key concepts (Class 10 Science (Physics))

The eye is a natural optical instrument that focuses light onto the retina, and its defects are corrected with lenses. This chapter also explains the phenomena the atmosphere produces — dispersion into a spectrum, the rainbow, twinkling stars and the blue sky.

Structure of the human eye

Light passes through the cornea, aqueous humour, pupil and lens to form an image on the light-sensitive retina.

Cornea and iris

The cornea does most of the refraction, while the coloured iris controls the size of the pupil and hence the light entering.

Retina and its cells

The light-sensitive screen at the back of the eye, carrying rod cells for dim light and cone cells for bright light and colour.

Power of accommodation

The ciliary muscles change the eye lens's curvature so that objects at different distances can be focused sharply.

Near point and far point

For a normal eye the near point is about 25 cm and the far point is infinity; the range between them is the field of clear vision.

Myopia (short-sightedness)

Distant objects appear blurred because the image forms in front of the retina; corrected with a concave lens.

Hypermetropia (long-sightedness)

Nearby objects appear blurred because the image would form behind the retina; corrected with a convex lens.

Presbyopia and cataract

Presbyopia is the age-related loss of accommodation, needing bifocal lenses; a cataract is a clouded lens, treated by surgery.

Dispersion of light

The splitting of white light into its component colours by a prism, because each colour is refracted through a different angle.

Spectrum

The band of seven colours (VIBGYOR) obtained by dispersion, with red deviated least and violet most.

Recombination of the spectrum

A second, inverted prism recombines the colours back into white light, proving white light is a mixture.

Rainbow

A natural spectrum formed when sunlight is refracted, internally reflected and refracted again by water droplets, always seen opposite the Sun.

Atmospheric refraction

Refraction through air layers of varying density, causing stars to twinkle and the Sun to appear early at sunrise and late at sunset.

Why stars twinkle but planets do not

Stars are point sources whose light varies as air fluctuates; planets are extended sources whose many points average out.

Scattering of light and the Tyndall effect

Scattering by fine particles makes the path of light visible; the amount of scattering depends on the size of the particles.

Blue sky and red sunrise

Air molecules scatter short blue wavelengths most strongly, making the sky blue; at sunrise light travels farther so only red survives.