Question

why conductors are not used in amplifiers where as we use semiconductors are used?

Answer 1

see you first must understand for better amplification purpose that is voltage gain should be high , this happens only when input resistance is high and output resistance is low. This sort of condition happens only when you have semiconductor.Because for forming a transistor which behave as amplifier...have either pnp/npn...this p and n are types of extrinsic semicondutor....but as know such thing doesn't exist with conductor.

Answer 2

As we have better control on the conductivity of semiconductor rather than metals. I mean by doping you can control the conductivity in semiconductor that is not case with conductors.

Answer 3

there may be three types of material- conductor, insulator or semi conductor
among these three, semi conductors are the only one whose conductivity can be controlled i.e. whose resistance can be varied according to potential applied at its terminals. For amplification this phenomenon is the basic one

Answer 4

the device "Mosfet" acts like a switch
if we use only conductors then the case will always have a closed switch
its semiconductors that give us an option of having both conductor and insualtor by the means of doping ... hence semiconductors