Which of the following calculates power dissipated by a series linear voltage regulator?

A series linear voltage regulator acts like a variable resistor placed in series with the load to maintain a constant output voltage. The power it dissipates as heat is calculated using the basic power formula P = E x I, where E is the voltage across the regulator itself and I is the current flowing through it. The voltage dropped across the regulator is the difference between the input voltage and the output voltage. The current flowing through the series regulator is essentially the same as the output current delivered to the load. Therefore, the wasted power dissipated as heat by the regulator is the voltage difference from input to output multiplied by the output current. Other options represent different power calculations entirely. Multiplying input voltage by input current gives the total power consumed by the entire circuit, while multiplying output voltage by output current calculates the useful power actually delivered to the load.