Q28 of 58 Page 346

‘Vision is one of the wonderful gifts given to us by God. But most of the people never take care of their eyes.’

(i) Care for eyes should be taken; suggest some methods for proper eye care.


(ii) What value is associated with a given statement?

(i) Care of eyes should be taken. Some ways as listed below


● Eating healthy food such as green vegetables and fruits.


● Don’t stress your eyes by working on computers or watching television for too long.


● Manage your weight and diet.


● Get proper sleep.


● Keep eyes away from harmful radiations


● Wear sunglasses while going out on a sunny day to protect eyes from UV rays


(ii) Value associated with the given statement is that we should be grateful to the God for giving us the precious gift of vision to see this beautiful world. We should take care of this gift throughout our life. We should also pass this priceless gift of vision by donating our eyes after death to those in need.


More from this chapter

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26

Do you know that the corneal-impairment can be cured by replacing the defective cornea with the cornea of the donated eye? How and why should we organize groups to motivate the community members to donate their eyes after death?

 27

A student finds the writing on the blackboard as blurred and unclear when sitting on the last desk of the classroom. He, however, sees clearly when sitting on the front desk at an approximate distance 2 m from the blackboard.

(i) Draw the ray diagram to illustrate the formation of image of the blackboard writing by his eye lens when he sits at the (a) last desk, (b) front desk


(ii) Name the defect of vision the student is suffering from. Also, list two causes of this defect.


(iii)Name the kind of lens would enable him to see clearly when he is seated at the last desk. Draw the ray diagram to illustrate how this helps him to see clearly.

 29

Sunil is a student of class VIII in a public school in Delhi. During summer vacation, his parents planned a visit to Haridwar by their car. During the journey from Delhi to Haridwar, Sunil sat on the front seat and his father was driving the car. Sunil observed that the road ahead on the highway appears to be wet but when the car reached the spot, road is found to be dry. He was perplexed by this observation. He asked his father. His father advised Sunil not to disturb him during driving and said that he will discuss the problem on reaching Haridwar. In the evening, when they were settled in a hotel at Haridwar, Sunil’s father told him that the illusion observed by Sunil was on account of atmospheric refraction. Now, Sunil was happy as he knew the real explanation of his observation.

(i) What is atmospheric refraction?


(ii) Name any two phenomena based on atmospheric refraction


(iii)What characteristic was shown by Sunil during his journey?


(iv) What advice was given by Sunil’s father to him and why?

 1

For a healthy eye, the rays of light entering the eye form a sharp image on retina. For a myopic eye, the rays from distant objects focus in front of the retina forming a blurred image. Which of the following lenses shown below will help to correct myopia?