Question: how to find how much power is dissipated by a resistor?
Answer: First, we use Ohm's law ( V = I × R ), to find the current through the resistor. The voltage across the resistor is V = 9 V. The resistance of the resistor is R = 100 ?. Then, we can use the power rule ( P = I × V ), to find the power dissipated by the resistor.