Answer to Question #72588 in Electricity and Magnetism for Patrick

Question

The speed sensor for an automotive cruise control consists of a
magnet mounted on the drive shaft along with a coil of wire
mounted on the chassis. As the magnet passes the coil, an emf is
induced for a short period of time. The number of induced emfs
occurring per second allows a computer to determine the drive
shaft speed and ultimately the speed of the car. What is the
polarity of the emf when the magnet is at the three positions A.
B, and C shown in the drawing? Assume the north pole of the
magnet is closest to the coil.