Class 10 Science - Chapter The Human Eye and the Colourful World NCERT Solutions | What is the far point and near point of

Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.

Explain why the planets do not twinkle.

Why do stars twinkle?

The human eye forms the image of an object at its

(a) cornea.          (b) iris.          (c) pupil.          (d) retina.

What is meant by power of accommodation of the eye?

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?

The least distance of distinct vision for a young adult with normal vision is about

(a) 25 m.          (b) 2.5 cm.          (c) 25 cm.          (d) 2.5 m.

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?

The change in focal length of an eye lens is caused by the action of the

         (a) pupil.                        (b) retina.
         (c) ciliary muscles.        (d) iris.

The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?

Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.

What is a good source of energy?

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What changes can you make in your habits to become more environment-friendly?

What is the difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Why should a magnesium ribbon be cleared before burning in air?

Define the principal focus of a concave mirror.

Why should curd and sour substances not be kept in brass and copper vessels?

Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.

Name two safety measures commonly used in electric circuits and appliances.

Find the power of a concave lens of focal length 2 m.

We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.

In the Modern Periodic Table, which are the metals among the first ten elements?

A solar water heater cannot be used to get hot water on

        (a) a sunny day.                (b) a cloudy day.
        (c) a hot day.                     (d) a windy day.

What changes would you suggest in your home in order to be environment-friendly?

The magnification produced by a plane mirror is +1. What does this mean?

On what basis would you classify energy sources as

(a) renewable and non-renewable?
(b) exhaustible and inexhaustible?

Are the options given in (a) and (b) the same?