What is the power of a concave lens whose focal length is -75.0 cm?
A convex lens of focal length 15 cm is kept in front of a concave lens of focal length 30 cm. What is the power of the two lens system?
The lens of power + 1.0 D is :
(a) convex of focal length 1.0 cm
(b) convex of focal length 1.0 m
(c) concave of focal length 1.0 cm
(d) concave of focal length 1.0 m
Focal length of a concave lens is 400 cm, then power of the lens is: