ElectronParade
An inductor is essentially a coil of wire. While a capacitor stores energy in an electrical field, an inductor stores energy in a magnetic field when current flows through it.
The Defining Trait of an Inductor
The most important thing to know about inductors is this: They resist changes in current.
- If current is flowing steadily, the inductor is happy and acts almost like a normal wire.
- If the current suddenly tries to increase, the inductor’s magnetic field pushes back, slowing the increase down.
- If the current suddenly tries to stop, the collapsing magnetic field pushes current forward, trying to keep the flow going.
How Inductors Are Used
Because inductors resist sudden changes in current, they are incredibly useful for stabilizing circuits and managing alternating signals.
- Filtering Power: In power supplies, inductors are used to “choke” out high-frequency noise and sudden voltage spikes, providing clean, steady DC power to sensitive components.
- Transformers: By placing two inductors (coils) next to each other, a fluctuating magnetic field in one coil can induce a voltage in the other coil without them physically touching. This is how power grids step voltage up for long-distance travel and step it down for your home.
- Wireless Charging: The charging pad for your phone contains an inductor coil. When alternating current flows through it, it creates a magnetic field. This field passes through the back of your phone, inducing a current in a second coil inside the phone, charging the battery wirelessly!
The Flyback Warning
Because inductors try to keep current flowing when you turn a circuit off, they can generate a massive, sudden spike in voltage (called voltage kickback or flyback). This is why you must always use a protective Diode (see Lesson 105) when turning off inductive loads like motors or relays!
Recommended Gear:
- Assorted Inductor Kit - Useful for building filters and power supplies.
- Breadboard Oscilloscope - The best tool for actually visualizing the noise that inductors filter out.