MOSFETs… n-channel MOSFET, p-channel MOSFET, how do you use them? What do they mean? An n-channel MOSFET is turned on when you supply a positive voltage to the gate, this allows positive voltage current to flow from drain to source. (The source provides a source of electrons.) A p-channel MOSFET is turned on when you supply a path to ground to the gate, this allows positive voltage current to flow from source to drain. (The source provides a source of holes.)
Yes, so in essence, control of MOSFETs is very much like PNP versus NPN BJT transistors: an n-channel MOSFET is like an NPN transistor, a p-channel MOSFET is like a PNP transistor. And, therefore, what I have previously written about current paths for BJT transistors is also somewhat applicable for MOSFETs too… just that not nearly as much current needs to flow through the gate of a MOSFET for it to operate.
It’s hard to fish that information out of Wikipedia, and there are definitely easier ways to explain for electronic circuit designers. You don’t need to know the full theory in this purpose.
20200322/https://en.wikipedia.org/wiki/MOSFET
20200322/https://en.wikipedia.org/wiki/NMOS
20200322/https://en.wikipedia.org/wiki/Field-effect_transistor#n-channel_FET
But, there is one theoretical point that is worthy of note when making purchasing decisions for MOSFETs. In general, when you are using a MOSFET to control power switching, you want to verify that the MOSFET you are buying is an enhancement mode MOSFET. This means that when there is no voltage applied, the MOSFET will not conduct, just like a BJT transistor. You can identify this clearly by looking at the schematic diagram for a MOSFET and verifying that there is a broken bar around the central arrow. A depletion-mode MOSFET, by contrast, will conduct when no voltage is applied, and an inverse voltage must be applied in order to turn it off. The schematic symbol will not have a broken bar around the arrow, the line will be connected to the rest of the edges.