Conditions for induced emf in a conductor

5.2 Conditions for induced e.m.f. in a conductor

This can only take place in the conductor when
1. there is relative motion between conductor (coil) and magnet (fig. 5.2.1b and fig 5.2.1c)
2. magnetic field lines are being cut by the conductor
3. cutting of the field lines must be perpendicularly to get maximum effect
4. the direction of e.m.f. depends on the direction of relative motion between conductor and direction of magnetic field lines (approach, fig. 5.2.1b and retreat, fig 5.2.1c)

Conditions for induced e.m.f. in a conductor

Summarizing, relative motion is needed between a magnet and a coil to produce induced e.m.f.s.  The induced e.m.f. increases when the relative velocity increases and when a soft iron core is used inside the coil.  The soft iron core concentrates magnetic field lines.