Each time the shutter speed setting decreases, what is the effect on the amount of light reaching the film?

When the shutter speed setting decreases, the amount of light reaching the film increases. This is because a decrease in shutter speed means the shutter remains open for a longer duration, allowing more light to enter and hit the film.

Shutter speed operates on a logarithmic scale in photography, where each full stop change in shutter speed effectively doubles or halves the amount of light. Specifically, decreasing the shutter speed from, for example, 1/100 of a second to 1/50 of a second allows double the amount of light to reach the film. Conversely, adjusting to a faster shutter speed (increasing the speed) would reduce the light entering the camera.

Thus, the appropriate choice reflects that each time the shutter speed setting decreases, the amount of light captured increases—specifically, by double.