Question

The reciprocal of focal length f of a concave lens is equal to the difference of reciprocals of the object distance v and the image distance u. Frame the formula for the following statement.

• A. $\frac{1}{f}=\frac{1}{u}+\frac{1}{v}$
• B. $\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$
• C. $\frac{1}{v}=\frac{1}{f}+\frac{1}{v}$
• D. $\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$

Answer 1

The correct option is D $\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$

Given that the reciprocal of focal length $f$ equals the difference of

reciprocals of $v$ and $u$, the formula is
$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$

So, option D is correct.