Draw ray diagrams showing the image formation by a concave lens when an object is placed.

(a) at the focus of the lens

(b) between focus and twice the focal length of the lens

(c) beyond twice the focal length of the lens.

Draw ray diagrams showing the image formation by a convex mirror when an object is placed.

(a) at infinity

(b) at finite distance from the mirror.

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle, screen and lens as under

Position of candle $=12.0 \mathrm{cm}$

Position of convex lens $=50.0 \mathrm{cm}$

Position of the screen $=88.0 \mathrm{cm}$

(i) What is the focal length of the convex lens?

(ii) Where will the image be formed if he shifts the candle towards the lens at a position of  $31.0 \mathrm{cm}$?

(iii) What will be the nature of the image formed if he further shifts the candle towards the lens?

(iv) Draw a ray diagram to show the formation of the image in case (iii) as said above.

If a laser beam is allowed to fall along the principal axis of a concave mirror, the ray will:

The correct ray diagram is

The image of a distant object is obtained on a screen by using a concave mirror. The focal length of the mirror is measured by the distance between