Certified Professional Photographer (CPP) Practice Exam

What role do photons play in the operation of a sensor?

1. They create pixels.

2. They absorb electrons.

3. They are converted to light.

4. They create an image.

The correct answer is: They absorb electrons.

Photons are fundamental particles of light, and their primary role in sensor operation relates to their interaction with the sensor's materials. When photons strike the sensor, they can be absorbed by the photoreceptive material, typically silicon in digital sensors. This absorption process transfers energy from the photons to the electrons in the sensor, exciting them and allowing them to move freely. This movement of electrons is critical as it generates an electric charge that is proportional to the intensity of the incoming light, forming the basis for the image capture process. Photons do not create pixels; instead, pixels are the individual units in an image that are made possible due to the absorption of these photons and the resulting electronic signals. While photons themselves are not converted to light, they interact with the sensor to produce electrical signals that represent the scene being captured, eventually leading to the creation of an image once the signals are processed. Therefore, the key role of photons in a sensor is their ability to cause the excitation of electrons and generate the electric signals necessary for image formation.