In terms of energy behavior, which statement about reactance is accurate?

• A. It dissipates energy as heat in a resistor
• B. It has no effect on energy flow
• C. It converts energy into light
• D. It stores energy and releases it after a quarter cycle

Answer: (D)

Reactance involves elements that store energy temporarily in their fields and then return that energy to the circuit. In ideal reactive components, this storage and release happen without net energy loss over a full cycle, because the average power is zero. The energy stored in an inductor is (1/2) L I^2 and in a capacitor is (1/2) C V^2, showing how energy is tied to current or voltage and exchanged with the source as the waveform cycles.

Because voltage and current are 90 degrees out of phase in a purely reactive element, energy is taken in from the source and stored during part of the cycle, then released back into the circuit in the next part. This means energy is stored and then returned after a quarter-cycle, which aligns with the observed phase relationship and the energy-storage nature of reactance.

This is why the statement about storing energy and releasing it after a quarter cycle is the accurate description. It’s not about dissipating energy as heat (that would describe a resistor), nor about having no effect on energy flow, nor about converting energy to light.