While an emf source supplies energy to a circuit, that energy is dissipated when the current passes through resistance. In dealing with circuits though, it is often more useful to know the rate at which energy is changing. As you may recall, this quantity is also known as power.Consider a resistor with resistance R. The current through the resistor is I, and the voltage across the resistor is V. Which of these formulae can be used to find the power drawn by the conductor?