So how we can relate power with voltage if P = Power, V = Voltage and I = Current.
The plate current, plate voltage and grid voltage of a 6F6 triode tube are related as ip=41(Vp+7Vg)1.41 Where Vp and Vg are in volts and ip in microamperes. The tube is operated at Vp=250V,Vg=−20V. Calculate (a) The tube current (b) the plate resistance, (c) the mutual conductance and (d) the amplification factor.