A symmetric double convex lens is sliced into two equal parts by a plane perpendicular to its principal axis. Given that the power of the original lens was 4 D , the power of one cut-lens will be

Step-by-step solution

The power of a symmetric double convex lens is given by P = ( - 1) ( 1 R - 1 -R ) = 2( - 1) R . Given P = 4 D . When the lens is sliced into two equal parts by a plane perpendicular to its principal axis, each part becomes a plano-convex lens with radii of curvature R and . The power of one such cut lens is P' = ( - 1) ( 1 R - 1 ) = - 1 R . Comparing the two expressions, we get P' = P 2 . Substituting the value of P , P' = 4 2 = 2 D .