What is the primary function of a MOSFET?

The primary function of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is to control current flow. This is achieved through the application of a voltage to the gate terminal, which creates an electric field that modulates the conductivity of a channel between the source and drain terminals. When a voltage is applied to the gate, it allows or prevents current from flowing, functioning effectively as a switch or voltage-controlled resistor. This capability to regulate current makes MOSFETs essential components in a wide array of circuits, including power amplifiers, power supplies, and digital switching circuits.

While some options mention various functions related to electronic components, they do not accurately represent the primary role of a MOSFET. Storing electrical charge is more aligned with capacitors, amplifying signals is more characteristic of transistors in general but does not encapsulate the primary role of all MOSFETs, and converting light into electrical signals pertains specifically to photodetectors or solar cells, not MOSFETs. Thus, controlling current flow stands out as the main function integral to the operation of a MOSFET in electronic applications.