Starting from Maxwell's equations, deduce Faraday's law of induction
dtdΦ=−ε
for a moving circuit C, where Φ is the flux of B through the circuit and where the EMF ε is defined to be
ε=∮C(E+v×B)⋅dr
with v(r) denoting the velocity of a point r of C.
[Hint: consider the closed surface consisting of the surface S(t) bounded by C(t), the surface S(t+δt) bounded by C(t+δt) and the surface S′ stretching from C(t) to C(t+δt). Show that the flux of B through S′ is −∮CB⋅(v×dr)δt.]