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Inductor

An inductor stores energy in a magnetic field when current flows through it. It prefers constant current and responds with a voltage proportional to how fast the current changes. In a DC circuit at steady state it behaves as a short circuit.

u = L\dfrac{di}{dt}

voltage as a function of the rate of change of current

E=\tfrac12LI^2

energy stored in the magnetic field

Symbols

$L$	inductance	H
$I$	current through the inductor	A
$u$	voltage across the inductor	V
$E$	stored energy	J

Example

$L=10$ mH carries $I=2$ A:

$E=\tfrac12LI^2=\tfrac12\cdot0.01\cdot4=0.02$ J.

The current through an inductor cannot jump instantaneously – only the voltage can.

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Part of Electric Circuits: Capacitors and inductors.