Triode — UPSC Physics Optional CSE 1987 Paper II

Draw the circuit diagrams suitable for measuring the voltage amplification of a triode valve with the following methods of connection: (a) Common cathode (b) Common grid (c) Common anode. Write down, without proofs, the expression for amplification in each case in terms of \mu and the relevant resistance values. Which of the three methods is usually employed in high frequency circuit practices and why ?