# inductance

Inductance, also called **self-inductance**, is the amount of magnetic
flux (*Φ*) produced for a given electric
current (*I *). Inductance *L* = *Φ* / *I*.
Another way of saying this is that inductance is the ratio of the voltage induced (see electromagnetic
induction) to the rate of change of the current.
It depends on the circuit geometry, being large for coils and small for
extended circuits, and is greatly increased by the presence of ferromagnetic materials.

Voltages induced by currents in a different circuit are measured in terms
of **mutual inductance**. Inductors have an impedance to AC circuits proportional to the current, and are widely used in electronics.