Question

The mirror formula is given by
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$ where the symbols have their usual meanings. Then the lens formula is given by

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

Answer 1

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

Mirror formula is
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
here symbols have their original meaning where as lens formula is given by
$\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$