How does the allowable power density for RF safety change if duty cycle changes from 100 percent to 50 percent?

Answer: C. It increases by a factor of 2

When duty cycle drops from 100 percent to 50 percent, the allowable power density increases by a factor of 2. Exposure limits are based on average exposure, and transmitting half the time halves the average. So the peak level can be twice as high for the same average.

Tip: Half the time on, twice the allowed level.