Consider now a single
coil/circuit/loop with N turns. As the current in the loop
changes the magnetic field and hence the magnetic flux through
the loop changes. This changing "self flux" through
Faraday's Law leads to an induced emf in the circuit,
so that the induced emf - sometimes called a "back emf" - is given by
This "back emf" always opposes the primary emf (due to Lenz's Law), as shown in the diagram at right.
From above, 
which can be compared to the similar equation
for capacitance 
.Renee Descartes walks into a bar, the bartender says 'sir can I get you a martini 'Descartes says 'I don't think...' and he disappears.
Dr. C. L. Davis
Physics Department
University of Louisville
email: c.l.davis@louisville.edu
