For transistor action
(1)  Base, emitter and collector regions should have similar size and doping concentrations.
(2)  The base region must be vety thin and lightly doped.
(3)  The emitter-base junction is forward biased and base-collector junction is reverse biased.
(4)  Both the emitter-base junction as well as the base-collector junction are forward biased.

Which one of the following pairs of statements is correct?

A common emitter amplifier has a voltage gain of 50, an input impedance of 100 $$\Omega $$ and an output impedance of 200 $$\Omega $$. The power gain of the amplifier is

Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has high melting point ?

The device that can act as a complete electronic circuit is