Class 10 Science - Chapter The Human Eye and the Colourful World NCERT Solutions | What is meant by power of accommodation

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

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.

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.

How many 176 Ω resistors (in parallel) are required to carry 5 A on a 220 V line?

Why is the use of iodised salt advisable?

Which of the following pairs will give displacement reactions?

(a) NaCl solution and copper metal
(b) MgCl₂ solution and aluminium metal
(c) FeSO₄ solution and silver metal
(d) AgNO₃ solution and copper metal.

You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

How would these advantages differ from the advantages of using a long-term perspective in managing our resources?

What are fossils? What do they tell us about the process of evolution?

In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?

A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.

Why is DNA copying an essential part of the process of reproduction?

State the principle of an electric generator.