A triode has a plate resistance of 10 k and an amplification factor of 20 . It is operated at a plate voltage of 250 V and a grid voltage of -7.5 V , resulting in a plate current of 10 mA . To what value must the grid voltage be adjusted in order to increase the plate current to 15 mA ?

Step-by-step solution

Given: Plate resistance, r_p = 10 k Amplification factor, = 20 Initial plate current, I_ p1 = 10 mA Final plate current, I_ p2 = 15 mA Initial grid voltage, V_ g1 = -7.5 V The mutual conductance g_m is given by: g_m = r_p = 20 10 k = 2 mA/V The change in plate current is: I_p = I_ p2 - I_ p1 = 15 mA - 10 mA = 5 mA For a constant plate voltage ( V_p = 0 ), the change in plate current is related to the change in grid voltage by: I_p = g_m V_g Substituting the values: 5 mA = 2 mA/V V_g V_g = 2.5 V The new grid voltage