Find the power of a convex lens of focal length 40 cm.

Find the power of a convex lens of focal length 12.5 cm.

Calculate the power of convex lens of focal length 15 cm.

Choose the correct alternative and write it along with its alloted alphabet: The power of a convex lens of focal length 25cm is………….

The power of convex lens of focal length 50 cm is______

What is the focal length 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 a diverging lens ? Ignore thickness of the lenses.

Solve the following examples/ numerical problems: An object of height 4cm is placed in front of a concave lens of focal length 40 cm. If the object distance is 60 cm, Find the position and height of the image .

Answer the following questions : An object is placed in front of a convex lens of focal length 20 cm. If the object distance is changed from 60 cm to 40 cm , what can you say about the size of the image relative to that of the object?

An upright object is placed at a distance of 40 cm in front of a convergent lens of focal length 20 cm. A convergent mirror of focal length 10 cm is placed at a distance of 60 cm on the other side of the lens. The position and size of the final image will be:

An object of height 4 cm is kept in front of a concave lens of focal length 20 cm. If the object distance is 30 cm, find the position and the height of the image .