Components
Inductance
An inductor opposes a change of current by inducing a voltage proportional to the rate of change: V = L × ΔI ÷ Δt. The energy stored in its magnetic field is E = ½ × L × I². Because the inductor resists changes in current, interrupting an inductive circuit can produce a large voltage spike, which is why a flyback path is used across relay coils and other inductive loads.
Inductance
V = L × ΔI ÷ Δt; E = ½ × L × I²
Variables and units
| Symbol | Quantity | Unit |
|---|---|---|
| V | Induced voltage | V |
| L | Inductance | H |
| ΔI | Change in current | A |
| Δt | Time interval | s |
| E | Stored energy | J |
Conditions of application
Ideal inductance with negligible winding resistance and capacitance. The voltage expression uses the average rate of change over the interval; use calculus for a continuously varying current.
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