What is the function of the ‘gate’ in a MOSFET?

The function of the 'gate' in a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is to control the flow of current between the source and drain terminals. When a voltage is applied to the gate, it creates an electric field that modulates the conductivity of the semiconductor channel underneath the gate oxide layer. This modulation allows the MOSFET to act as a switch or an amplifier, effectively controlling current flow without the need for a direct electrical connection between the input (gate) and output (source-drain).

The other options pertain to functions that are not served by the gate. For instance, the gate does not act as a power source, dissipate excess heat, or directly increase voltage; instead, it influences the current that flows through the device based on the voltage applied to it. This capability is vital in digital and analog circuit design, allowing for precise control of electrical signals.