What is the primary function of a phototransistor?

The primary function of a phototransistor is to control electrical current based on light exposure. Phototransistors are semiconductor devices that can convert light energy into electrical energy, allowing them to act as a switch or amplifier in response to varying levels of light. When light hits the phototransistor, it generates charge carriers that facilitate current flow. This property enables phototransistors to be used in applications such as light detection, optical switches, and automated lighting systems.

Although amplifying sound signals, converting electrical signals into light, and storing electrical energy are functions associated with other electronic components, they do not describe the specific operation of a phototransistor. The focus on controlling electrical current in response to light makes this primary function particular to phototransistors.