How do I determine the power reqirements of a resistor with pulsing. .g. if a 2W resistor can handle 2A continuous, can it handle 20A at 10% duty cycle, or at 1% duty cycle. What about the ontime, is there a difference if using 250us on time/25ms offtime versus 250ms ontime/25s offtime. Will it vary from resistor to resistor.