English Medium Class 10 - CBSE Question Bank Solutions for Science

A young man has to hold a book at arm's length to be able to read it clearly. The defect of vision is:
(a) astigmatism
(b) myopia
(c) presbyopia
(d) hypermetropia

The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called:
(a) myopia
(b) presbyopia
(c) colourblindness
(d) cataract

The picture given here shows a person wearing ‘half-moon’ spectacles. What sort of eye-defect do you think he has? Why are these particular spectacles useful to him?

A short-sighted person has a near point of 15 cm and a far point of 40 cm.
(a) Can he see clearly an object at a distance of:
(i) 5 cm?
(ii) 25 cm?
(iii) 50 cm?
(b) To see clearly an object at infinity, what kind of spectacle lenses does he need?

The near point of a long-sighted person is 50 cm from the eye.

1. Can she see clearly an object at:
   1. a distance of 20 cm?
   2. at infinity?
2.  To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?

To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?

A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:

1. if the person is an old man
2. if the person is a young man

A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:  

if the person is a young man 

What does one mean by endothermic reaction? Give example.

A person is unable to read a book placed closer than 1 meter from his eyes. Identify the defect of vision in his eyes. Draw the ray diagrams to show the defect of vision and its correction.

A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.

A student cannot see a chart hanging on a wall placed at a distance of 3 m from him. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagrams for the (i) defect of vision and also (ii) for its correction.

State one role of ciliary muscles in the human eye.

An old man cannot see objects closer than 1 m from the eye clearly. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagram for the (i) defect of vision and also (ii) for its correction.

What eye defect is hypermetropia? Describe with a ray diagram how this defect of vision can be corrected by using an appropriate lens.

What is Hypermetropia (far sightedness)? 

Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.

List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision. 

When do we consider a student sitting in the class to be myopic? List two causes of this defect. Explain using a ray diagram how this defect of eye can be corrected.