Transistors provide this isolation, but the microscopic physics of nonlinear optical processes and stimulated emission typically does not. Ideally, we want a device with separate input and output ...

Transistors do not create electric current, they only control electric current supplied to them. The input current at the base controls the output current flowing between the emitter and the ...

Of course, a transistor in a telephone or in a radio has to handle complex signals. The output contact can't just amplify a steady hum of current, it has to dutifully replicate a person's voice ...