An equiconvex lens of focal length F is cut in to two equal parts along the vertical axis. The focal length of each part will be

Step-by-step solution

Using the lens maker's formula for the initial equiconvex lens: 1 F = ( - 1) ( 1 R - 1 -R ) = 2( - 1) R When the lens is cut into two equal parts along the vertical axis, each part becomes a plano-convex lens with radii of curvature R and . The focal length F' of each part is given by: 1 F' = ( - 1) ( 1 R - 1 ) = - 1 R Comparing the two equations: 1 F' = 1 2 ( 2( - 1) R ) = 1 2F F' = 2F Answer: 2F