Methods of producing induced emf
We know that the induced emf is given by the expression
e = – dφ/dt = – d/dt
= − (NBA cos θ)
Hence, the induced emf can be produced by changing
(i) the magnetic induction (B)
(ii) area enclosed by the coil (A) and
(iii) the orientation of the coil (θ) with respect to the magnetic field.