1. The LM7815 is used with an input voltage that can vary from 18 to 25 V. What is the maximum efficiency? The minimum efficiency?
2. A dc-to-dc converter has an input voltage of 5 V and an output voltage of 12 V. If the input current is 1 A and the output current is 0.25 A, what is the efficiency of the dc-to-dc converter?