Inductor
An inductor is a passive electrical component, typically a coil of wire, that stores energy in a magnetic field when current flows through it and opposes changes in current through electromagnetic induction. Its inductance (measured in henries) quantifies the ratio of the magnetic flux linkage to the current. Inductors are essential in filters, oscillators, transformers, and switching power supplies.
Key Formula
V_L = L × (dI/dt)
LaTeX: V_L = L \dfrac{dI}{dt}
| Symbol | Meaning | Unit |
|---|---|---|
| V_L | Voltage across inductor | Volt (V) |
| L | Inductance | Henry (H) |
| dI/dt | Rate of change of current | Ampere per second (A/s) |
Worked Example
Problem
A 50 mH inductor carries a current that increases from 0 to 4 A in 0.02 s. Find the induced EMF.
Solution
Step 1: L = 50 mH = 0.05 H. Step 2: dI/dt = (4 − 0) / 0.02 = 200 A/s. Step 3: V_L = L × dI/dt = 0.05 × 200 = 10 V.
Answer
V_L = 10 V
Energy Storage Comparison: Inductor vs Capacitor
| Property | Inductor | Capacitor |
|---|---|---|
| Stores energy in | Magnetic field | Electric field |
| Energy formula | E = ½LI² | E = ½CV² |
| Opposes change in | Current | Voltage |
| Unit | Henry (H) | Farad (F) |
| Symbol in circuit | Coil (─⌇⌇⌇─) | Two parallel lines (─||─) |
| AC behaviour | Impedance increases with frequency | Impedance decreases with frequency |
Interactive Tools
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Related Terms
Capacitor
A capacitor is a passive electronic component that stores electrical energy in an electric field between two conducting plates separated by an insulating material called a dielectric. The capacitance (measured in farads) quantifies how much charge a capacitor stores per unit voltage. Capacitors are widely used in circuits for filtering, energy storage, timing, and coupling or decoupling signals.
Transformer (electrical)
An electrical transformer is a static electromagnetic device that transfers electrical energy between two or more circuits through electromagnetic induction, typically changing the voltage and current levels while keeping frequency and power (ideally) constant. It consists of a primary coil and one or more secondary coils wound around a shared iron core. Transformers are indispensable in power transmission, allowing high-voltage transmission over long distances to reduce resistive losses.
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials, exerting a force on them perpendicular to their velocity. It is represented by the magnetic flux density B (measured in tesla) and arises from electric currents, changing electric fields, and intrinsic magnetic moments of elementary particles. Magnetic fields are central to the operation of motors, generators, MRI machines, and data storage devices.
From Latin "inducere" meaning "to lead in" or "to introduce", related to electromagnetic induction. The unit Henry honours American scientist Joseph Henry (1797–1878) who independently discovered electromagnetic induction around the same time as Michael Faraday in the 1830s.