We take a derivative (or differentiate) whenever we want to find the rate at which one quantity varies with respect to another. Common examples are velocity, which is the rate at which position changes with time, and acceleration, which is the rate at which velocity changes with time. We will encounter other important rates during our study of electricity and magnetism. To carry out calculations involving derivatives, you must know formulas for the derivatives of various functions. You are expected to memorize the following table:
