Which of the following statements is true ?

Options

A. A convex lens with power + 4D has a focal length -0.25 m
B. A convex lens with power - 4D has a focla length + 0.25 m
C. A concave lens with power + 4D has a focal length - 0.25 m
D. A concave lens with power - 4D has a focal length - 0.25 m

Answer

D

Explanation

P and f of concave lens is (-ve)
`P = (1)/(f) rArr - 4 (1)/(f)`
rArr = - `(1)/(4) = - 0.25`m.