MOSFET, short for Metal-Oxide-Semiconductor Field-Effect Transistor, is a field-effect transistor that can be widely used in analog circuits and digital circuits. MOSFETs can be divided into N-channel type with the majority of electrons and P-channel type with the majority of holes according...
Meaning with no signal the mosfet gate is grounded and there's no load. But as you feed it signal from the function generator, that brings the gate up and turns the mosfet on loading the supply. And if you make the cap and drain resistor smallish, you could actually make an AC load...