Question

An equal convex lens of focal length f was cut into two equal parts along a line perpendicular to the principle axis. The focal length of each half is

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

Answer 1

The correct option is C 2f

$f=\frac{R}{2(\mu -1)}\to \left(1\right)$
after culting
$f^1=\frac{R}{({\mu }_1-1)}\to \left(2\right)\frac{\left(2\right)}{\left(1\right)}=\frac{f_1}{f}=2;f^1=2f$