Question

A camera objective has an aperture diameter of d. If the aperture is reduced to diameter d/2, the exposure time under identical conditions of light should be made ______.

पर्याय

• ${\displaystyle \sqrt{2}}$ fold

• 2 fold

• ${\displaystyle 2\sqrt{2}}$ fold

• 4 fold

Answer 1

A camera objective has an aperture diameter of d. If the aperture is reduced to diameter d/2, the exposure time under identical conditions of light should be made 4 fold.

Explanation:

Time of exposure ∝ ${\displaystyle \frac{1}{{\left(\text{Aperture}\right)}^2}}$

${\displaystyle \frac{t_2}{t_1}={\left(\frac{d_1}{d_2}\right)}^2={\left(\frac{d_1}{d_1\text{/}2}\right)}^2=4}$