The light coming through the aperture is proportional to the area so to double the light you need to double the area. How much do you need to increase the radius by to double the area?
When taking a photo with a camera in manual mode, one needs to set the
focus, the shutter speed and the exposure. The latter is controlled by ad-
justing the size of aperture, the circular opening that allows light to hit the
film or image sensor when the shutter is opened.
Suppose an aperture opening has a radius of r. What radius R would the
aperture need to be changed to to allow twice as much light through it?
Hint: The area of a circular region is given by A = (pie) r squared.
If twice as much light is to pass through the aperture, the radius needs to be increased so
that the area of the circular aperture doubles.
I honestly do not understand the question and find it confusing. Can someone please help me figure this question out.