A bi convex lens of focal length 10 cm is cut in two identical parts along a plane perpendicular to the principal axis. The power of each lens after cut is _____ D .

Step-by-step solution

The focal length of the bi-convex lens f can be calculated as follows: 1 f = ( μ - 1 ) 1 R - 1 - R = 2 μ - 1 R       . . . 1 When the lens is cut into two halves, the focal length f ' of each part can be calculated as follows: 1 f ' = ( μ - 1 ) 1 R - 1 ∞ =   μ - 1 R       . . . 2 Hence, the ratio of the powers for both the lenses can be given by P ' P = 1 f ' 1 f =   f f ' = μ - 1 R 2 μ - 1 R = 1 2 ⇒ P ' = &#16