Briefly explain how a Transistor can be used as a Switch and as an Amplifier?

In the circuit below, we would like to bias the transistor 5) such that it operates in the active region. (Assuming that we want to have a dc collector current of Ic = 1mA, VBE = 0.7V and B = 100.) +10V +10V R, S Iel> Rc 80k? a) Find the Vihevenin and Rahevenin equivalent for the shaded region of the circuit. B= 100 3 RE 20k b) Find the value of Rg which places the transistor in the active region with I, = 1mA c) Find the value of R. which are also suitable for keeping the transistor in the active region with Ie = 1mA.