When the magnet is moved near the coil made of wire, the number of magnetic field lines produced by magnet passing through the coil changes. This change in the number of magnetic field lines passing through the coil induces current in the coil. It is the rate of change in the number of field lines passing through the loop that determines induced voltage in the coil. We need to determine Magnetic Flux which is same as electric flux. The magnitude of induced emf in a coil is equal to the rate of change of magnetic flux.