Solve these physics exams questions with detailed solutions. I took these questions from past exams. I want to revise on these it's like to come up in my upcoming exams. Be able to draw diagrams

Be able to derive the formulae for electric field in a pn junction by integrating the charge density (given Gauss's equation) on both sides of the junction. Understand the effect of bias (positive and negative) on a pn junction in terms of its effect on the bandstructure and therefore current. Be able to explain how a JFET works on terms of voltage control of its depletion regions formed at the pn junctions. Be able to draw diagrams of a JFET under different bias conditions. Be able to draw IV versus gate voltage for a JFET. Be able to explain and draw circuit diagrams of how a JFET can act as a small signal amplifier