A photocell is a resistor that changes resistance depending on the amount of light incident on it. A photocell operates on semiconductor photoconductivity: the energy of photons hitting the semiconductor frees electrons to flow, decreasing the resistance. An example photocell is the Advanced Photonix PDV-P5002, shown in Figure 21.2.
A: Photocells are specifically designed to detect light and changes in light intensity. They convert light energy into electrical energy through the photoelectric effect. As such, photocells are not capable of directly detecting other types of energy like sound or heat.
The photocell is one kind of sensor, which can be used to allow you to sense light. The main features of photo-cell include these are very small, low-power, economical, very simple to use. Because of these reasons, these are used frequently in gadgets, toys, and appliances. These sensors are frequently referred to as Cadmium-Sulfide (CdS) cells.
A photocell or photoresistor is a sensor that changes its resistance when light shines on it. The resistance generated varies depending on the light striking at his surface. A high intensity of light incident on the surface will cause a lower resistance, whereas a lower intensity of light will cause higher resistance.
The spectral response of a photocell refers to its sensitivity to different wavelengths or colors of light. Different types of photocells have varying degrees of sensitivity across the electromagnetic spectrum, with some being more responsive to specific colors of light than others.
Observe the reading on the multimeter as the photocell is exposed to the light. The resistance value should decrease significantly compared to the dark resistance value previously measured. This decrease in resistance indicates the photocell’s responsiveness to light.