Inductors

A coil of wire that resists sudden changes in current.

An inductor is usually just a coil of wire, sometimes wound around a magnetic core. When current flows through it, it creates a magnetic field; that field, in turn, resists any sudden change in the current — the opposite tendency to a capacitor, which resists sudden changes in voltage.

• Measured in henries (H) — most practical values are millihenries (mH) or microhenries (µH).
• Found in power converters, filters, and anywhere a magnetic field is put to work (motors, relays, speakers).
• Beginner circuits use inductors far less often than resistors or capacitors.