Question
Two lenses have power of (i) + 2D (ii) - 4D. What is the nature and focal length of each lens?
Solution
Given, two lenses.
(i) Here,
Power, P = + 2D
Focal length,
Since, the focal length is positive, the lens is convex.
(ii) Here,
Power, P = - 4D
Focal length,
Negative sign of the focal length implies that the lens is concave.
