An image magnified `2/3` times is produced by a convex mirror of focal length 20 cm. Find the object distance.

Find the power of a convex lens of focal length 25 cm.

A man used a concave lens of focal length 20cm.Find the power of the lens.

An object is placed at a distance of 30cm from a concave mirror of focal length 20 cm. Find the position, nature and the magnification of the image. Draw a ray diagram.

An object is placed at a distance of 10cm from a convex mirror of focal length 15cm. Find the position and nature of the image.

An object of size 7.0cm is placed at 27cm in front of a concave mirror of focal length 18cm. At what distance from the mirror should a screen be placed,so that a sharp focussed image can be obtained? Find the size and the nature of the image.