hi, we say amplification µ=plate resis.(rp) x gm = δVp/δVg=plate voltage/grid voltage but im confused where is the amplification taking place it is just that to maintain the same plate current we have to EXTERNALLY increase the plate voltage,δVp, in response to an decrease in grid voltage,δVg. Also i have one more doubt that, since we do not make the grid voltage positive w.r.t. cathode so amplification cannot take place as the presence of -ve voltage on grid will only restrict the no. of electrons reaching the plate.