A diverging lens has a negative focal length.

A thin converging lens has a focal length f in air. If it is completely immersed in a liquid , briefly explain how the focal length of the lens will vary?

A converging lens has a focal length of 20 cm in air. It is made of a material of refractive index 1.6. If it is immersed in a liquid of refractive index 1.3, what will be the new focal length? How does the nature of the lens change. If this lens is immersed is a liquid of refractive index 1.8 ?

A converging and a diverging lens of equal focal lengths are placed co-axially in contact. Find the power and the focal length of the combination.

An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm.

A diverging lens of focal length f is cut in two identical parts each part forming a plano concave lens. What is the focal length of each part?

A convergent beam of light passes through a diverging lens of focal length 0.2 m and comes to focus at distance 0.3 m behind the lens.Find the position of the point at which the beam would converge in the absence of the lens.

A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The mirror and lens are likely to be:

A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The mirror and lens are likely to be:

A convex lens has 10 cm focal length in air.What is its focal length in water? (Refractive index of air-water is 1.33, refractive index for air glass = (1.5)