How much real power is consumed in a circuit consisting of a 100-ohm resistor in series with a 100-ohm inductive reactance drawing 1 ampere?
Why Only resistance dissipates real power; reactance stores and returns energy each cycle, so it consumes none. Real power is P = I squared times R, using just the resistive part: 1 A squared times 100 ohms = 100 watts. The 100-ohm inductive reactance contributes reactive power (VARs), not watts.
Watch out The 141.4 watt choice comes from using the impedance magnitude, sqrt(100^2 + 100^2) = 141.4 ohms, which gives apparent power in volt-amperes, not real power in watts. The 200 watt choice wrongly adds resistance and reactance as if both dissipated power.
Watts come from ohms of resistance only: P = I squared R. Reactance gets VARs, never watts.