What are J-FET transistors, and how do they work?

I'd like a fairly accurate and not incredibally answer is complex. Note: I am primarily interested in physics. Note: I'm mostly interested in physics (yeah, I probably should have asked this question in another section, but apparentally yahoo will not let me change it.

If my memory serves ... J-FET has three terminals .. gate, source and drain. It works, almost like plumbing parts terminals are named after. The current is allowed to flow from source to the drain voltage at the gate is raised.

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