Question

An inductor ‘L’, and a resistor ‘R’, are connected in series to an a.c source. The potential drop across inductor is 160 watts and that across the resistance ‘R’ is 120 volt. Find the virtual value of the applied voltage. Is algebric sum of the potential drops across L and R more than this value? If yes, resolve the paradox.

Answer 1

Hence algebric sum of p.d. across L and R ((160 + 120) V = 280 V) is more than the virtual or rms value of applied voltage. This is due to the phase relation between (V_L)_rms and (V_R)_rms . The potential drop, across the inductor, is ahead of potential drop across resistor by a phase angle of π/2. Therefore, they cannot be added like pure numbers. We need to add them by using the rule for ‘vector’. This type of ‘addition’ gives