Induced EMF Calculator (Faraday's Law)
Calculate the induced EMF from changing magnetic flux (Faraday's law) or from motional EMF (B·L·v).
Essential for generator and transformer design.
Induced EMF
Faraday’s law of electromagnetic induction states that a changing magnetic flux induces an EMF in a coil:
EMF = −N × ΔΦ/Δt
The motional EMF (conductor moving through a magnetic field) is:
EMF = B × L × v
Where:
- EMF = Induced electromotive force (volts, V)
- N = Number of turns in the coil
- ΔΦ = Change in magnetic flux (webers, Wb)
- Δt = Time interval (seconds)
- B = Magnetic field (Tesla)
- L = Length of conductor (meters)
- v = Velocity of conductor perpendicular to B (m/s)
Lenz’s Law: The negative sign in Faraday’s law reflects Lenz’s law: the induced EMF creates a current that opposes the change in flux. This is a consequence of conservation of energy.
Applications:
- Electric generators: Rotating coils in a magnetic field create continuously changing flux → AC electricity
- Transformers: Alternating current creates time-varying flux → induced voltage in secondary coil
- Induction charging: Phone wireless chargers use changing magnetic flux to induce current
- Eddy currents: Metal detectors and induction braking rely on induced currents in conductors
Induced current: If the coil has resistance R, the induced current is I = EMF/R.