CBSE – 10th Standard Science

Class 10 Question Bank Chapter 11 – The Human Eye and the Colourful World

Q1. What is accommodation?

Ans. The ability of the eye to focus both near and distant objects, by adjusting its focal length, is called the accommodation of the eye.

Q2. What are main parts of visual System?

Ans cornea, pupil, eye lens, aqueous humour and vitreous humour retina and the optic nerve are main parts of visual system.

Q3. What is myopia? What kind of lenses is used to correct it?

Ans. Myopia is short-sightedness and the image of distant objects is focused

before the retina it  is corrected by using a concave lens.

Q4 what is cataract?

Ans. When the crystalline lens of people at old age becomes milky and cloudy then that condition is called cataract, it causes partial or complete loss of vision.

Q5. What is Presbyopia?

Ans. This arises due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens due to aging.

Q6. Why do stars twinkle?

Ans. Twinkling of stars is due to atmospheric refraction of starlight. The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth.

Q7 Explain why the planets do not twinkle.

Ans. The planets are much closer to the earth, and are thus seen as extended sources there light source is nullified by average sources of light on earth so they don’t twinkle.

Q8 .Why does the Sun appear reddish early in the morning?

Ans. The Scattering of light through thicker layer and passing larger distance in the horizon causes reddening of the Sun at sunrise and sunset.

Q9. Why does the sky appear dark instead of blue to an astronaut?

Ans. There is no atmosphere and no scattering of light is done at such height thus the sky appears dark to astronauts.

Q10. Who cannot donate eyes?

Ans. Persons who were infected with or died because of AIDS, Hepatitis B or C, rabies, acute leukemia, tetanus, cholera, meningitis or encephalitis cannot donate eyes.

Q11. What are the functions of Eye Banks?

Ans. Eye bank collects, evaluates and distributes the donated eyes. All eyes donated are evaluated using strict medical standards.

Q12 Why does danger signal lights are red in colour?

Ans. Danger signals are red in coloured because red is least scattered by fog or smoke. Therefore, it can be seen in the same colour at a distance.

Q13.  who used a glass prism first to obtain the spectrum?

Ans. Isaac Newton was the first to use a glass prism to obtain the spectrum of sunlight.

Q14. What is far and near points of normal eye?

Ans. The smallest distance, at which the eye can see objects, clearly is called the near point of the eye 25 cm. and farthest point up to which the eye can see objects is far point that is infinity.

Try these:-

What is meant by power of accommodation of the eye?

A person with a myopic eye cannot see objects beyond 1.2 m distinctly.

What should be the type of the corrective lens used to restore proper vision?

 What is the far point and near point of the human eye with normal vision?

 A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?