How a changing magnetic field makes an emf. Magnetic flux, Faraday's laws of induction, Lenz's law and conservation of energy, and the emf in a rod moving through a field.
3 lessons, about 2 h5 simulations11 problems8 practice questionsPython in every lesson
Created by StemPy LabA changing magnetic flux through a coil makes an emf. The flux is , in weber. Faraday's law gives the size of the emf, . The charge that flows is , whatever the time taken.
The induced current flows in the direction whose own magnetic field opposes the change of flux that causes it. This is the law of conservation of energy at work, and it is the reason for the minus sign in .
A rod of length that moves at speed at right angles to a field has an emf between its ends. On rails with a resistance it carries a current . The force that you must apply is , and the power is , which all becomes heat.
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