How this calculator works
Faraday law relates induced emf to the rate of change of flux linkage. The finite-time expression returns an average voltage; it is instantaneous only when flux changes linearly. Field mode assumes a uniform field, fixed coil area, fixed angle and identical flux through every turn. The minus sign expresses Lenz law relative to a chosen winding and surface orientation.
Formula
emf_avg = -N deltaPhi/delta t. For fixed geometry, deltaPhi = A (Bfinal - Binitial) cos(theta), where theta is measured from the area normal.
Worked example
Ten turns with flux increasing by 2 Wb per turn over 4 s produce -5 V. Twenty turns of area 0.1 m² with a normal field increasing from 1 T to 3 T over 2 s produce -2 V.
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Frequently asked questions
Does flux already include the number of turns?
Enter flux per turn. The calculator multiplies by N once to form total flux linkage.
What angle should I enter?
Use the angle between the field axis and the perpendicular normal to the coil plane.
Does zero flux change induce voltage?
No for this fixed winding. A zero change gives zero average emf; it cannot recover a unique elapsed time from zero voltage.