Find the power of a concave lens of focal length 2 m ?

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

Calculate the focal length of the combination of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm. Is the system a converging or diverging lens?

A person having a myopic eye uses a concave lens of focal length 20 cm. What is the power of the lens?

An object is placed at a distance of 50 cm from a concave lens of focal length 20 cm. Find the nature and position of the image.

An object is placed 30cm away from a concave lens of focal length 15cm. Find the position, size and nature of the image.