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Energy in an inductor
Intermediate
Energy stored in magnetic field.
U = ½LI²U = ½LI², stored in the magnetic field. Energy density u = B²/2μ₀.
L = 2 H, I = 3 A: 9 J.
Releases suddenly when the current is cut.
In more detail
An inductor stores energy in its magnetic field, U = ½LI². Like a capacitor stores energy in an electric field, an inductor stores energy magnetically.
Real-world uses
- Switching power supplies use inductors to store energy.
- Ignition coils store energy for spark plugs.
- Engineers using inductors in power supplies calculate how much energy is stored in them when a current flows.
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Frequently asked questions
Where is the energy stored?
In the magnetic field inside and around the coil.
Why is the half there?
Because current builds up steadily from zero, so the average current is half the final value.
Where is the energy stored?
In the magnetic field inside and around the coil, which is released when the current falls.
Related topics in Magnetism & Induction
Eddy current braking · Self-inductance · Inductance of a solenoid · Mutual inductance · Transformer · Transformer losses