Q25 of 284 Page 240

Your eye contains a convex lens. Why is it unwise to look at the sun?

It is unwise to look at the sun because the convex lens focusses a lot of sun rays into our eyes and this may damage the eyes.


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24

Describe with the help of a ray diagram the nature, size and position of the image formed when an object is placed at infinity (considerable distance) in front of a convex lens. State three characteristics of the image so formed.

 25

What type of lens is shown in the diagram on the right ? What will happen to the parallel rays of light? Show by completing the ray diagram.

 26

Where the object must be placed for the image formed by a converging lens to be:

(a) Real, inverted and smaller than the object?


(b) Real, inverted and same size as the object?


(c) Real, inverted and larger than the object?


(D) Virtual, upright and larger than the object?

 27

Draw a diagram to show how a converging lens held close to the eye acts as a magnifying glass. Why is it usual to choose a lens of short focal length for this purpose rather than one of long focal length?