Question

A thin symmetrical double convex lens of power $P$ is cut into three parts $(A,B,C)$, as shown in the figure. Power of $A$ is:

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

Answer 1

The correct option is D $P$

Power of lens is
$P=(\mu -1)(\frac{1}{R_1}-\frac{1}{R_2})$

For $A$, since $\mu ,R_1$ and $R_2$ are the same as of the original lens,
$P_A=P$