Question

$A$ thin, symmetric double convex lens of power $P$ is cut into three parts $A,B$ and $C$ as shown. The power of -

• A. $C$ is $P$
• B. $A$ is $2P$
• C. $B$ is $\frac{P}{2}$
• D. $B$ is $\frac{3}{2}P$

Answer 1

Answer: (C)

$f_{B}=f_{c},\frac{1}{f_{A}}=\frac{1}{f_{B}}+\frac{1}{f_{c}}=P_{B}+P_{C}=2P_{B}=P$