38. An equiconvex lens is cut into two halves along (i) XOX and (ii) Y OY as shown in the figure. Let f, f′, f′′ be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively. Choose the correct statement from the following.

38. An equiconvex lens is cut into two halves along (i) XOX and (ii) Y OY as shown in the figure. Let f, f′, f′′ be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively. Choose the correct statement from the following.

(a) f = 2f, f′′ = 2f

(b) f = 2f, f′′ = f

(c) f′ = f, f′′ = 2f

(d) f′ = f, f′′ = f

Answer :  (c) f′ = f, f′′ = 2f