True or false
The power of a convex lens of focal length 2m is 1/2 dioptre.

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

Power of a lens is -5d, its focal length is:

What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.

The power of a lens is 2 dioptre its focal length will be…. .

Find the radius of curvature of the convex surface of a plano convex lens,whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5/

The size of the image of an object,which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm. If a concave lens of focal length 20 cm is placed between the convex lens and the image at a distance of 26 cm from the convex lens, calculate the new size of the image