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 ______.

Options

• `sqrt2` fold

• 2 fold

• `2sqrt2` 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 ∝ `1/("Aperture")^2`

`t_2/t_1 = (d_1/d_2)^2 = (d_1/(d_1"/"2))^2 = 4`