What refers to the time-averaged rate of energy transfer?

• A. Duty Factor
• B. Peak Power
• C. Average Power
• D. Exposure Duration

Answer: (C)

The time-averaged rate of energy transfer is the average power. Power is how fast energy is moved or transformed, and when the system operates in bursts or cycles, you look at the total energy moved over a complete cycle and divide by that cycle’s duration. In other words, P_avg = total energy transferred over the cycle ÷ cycle time, or P_avg = (1/T) ∫ P(t) dt. This is the quantity that governs effects like heating over time.

Duty factor is the fraction of time the energy transfer is actually happening within a cycle; it relates to average power when you know the peak power, via P_avg = P_peak × duty factor. Peak power is the instantaneous rate at the moment energy transfer is happening, not the averaged rate. Exposure duration is simply how long the system is active, not how much energy is transferred per unit time on average.