Question

The diaphragm in a photographic camera controls
(A) The amount of light entering the camera
(B) The subject to be photographed
(C) Both a and b
(D) None

Answer 1

Hint
Diaphragm is placed near the lens of the camera to cover it. It is mainly used to control the amount of light entering the camera. It changes the size of the opening thereby enabling different levels of light to enter and reach the sensor.

Complete step by step answer
A diaphragm is a thin opaque structure with an opening (aperture) at its centre. The main objective of the diaphragm is to stop or limit the passage of light. It only allows a limited number of photons to pass through the aperture. Thus, it is also called an aperture stop if it limits the brightness of light reaching the focal plane; or a field stop or a flare stop if it is used for some other different function.
Therefore, the correct answer should be option (A).

Note
Diaphragm is a covering which controls the opening and regulates the light entering the sensor. Shutter is also a device which works in a similar way, it controls the exposure time that is the lens aperture opened to admit light. Shutter can limit the exposure time or duration for which light is admitted.