An inductor is a passive electronic component that stores energy in a magnetic field when electrical current flows through it. Its main role in electronic circuits is to oppose changes in current, making it useful for filtering, energy storage, and tuning.
🧲 How Inductors Work
- An inductor is typically a coil of wire.
- When current flows through it, a magnetic field builds around the coil.
- If the current changes, the magnetic field changes — and this change induces a voltage (per Faraday’s Law) that opposes the change in current.
🧠 Key behavior:
- Inductors resist changes in current, just like capacitors resist changes in voltage.
📏 Key Formula
- V: Induced voltage
- L: Inductance (measured in henrys, H)
- dt/dI: Rate of change of current
🔧 Common Roles of Inductors in Circuits
- Role Description
- Filtering (LC or LRC circuits) Blocks high-frequency noise or AC, while allowing DC or low-frequency signals
- Energy storage In power supplies (e.g., buck/boost converters), stores and transfers energy
- Chokes Blocks or “chokes” high-frequency AC while passing DC
- Transformers Uses inductors in pairs to transfer energy between circuits (via mutual inductance)
- Tuning circuits (LC tanks) Used with capacitors to select specific frequencies (e.g., in radios)
🧠 Simple Analogy
- Think of an inductor like a flywheel in a machine:
- Once spinning (current flowing), it wants to keep spinning.
- If you try to stop it suddenly (change current quickly), it pushes back.
🧪 Real-World Examples
- Device How Inductors Are Used
- Switching power supply Stores and releases energy to maintain stable voltage
- Radio receiver Tunes to a specific frequency
- Speaker crossover Filters out high or low frequencies
- Relay coil Creates a magnetic field to move contacts
⚠️ Key Behavior to Remember
- Inductors allow DC to pass after a brief delay.
- They block fast-changing AC signals (especially high frequencies).
- They oppose sudden changes in current flow.
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