Electromagnetic Induction Mind Map

Magnetic flux through a surface is the measure of the magnetic field passing normally through that surface. For a uniform magnetic field, it is given by Phi_B = B A cos theta.

Always identify the area vector first. If the question gives the angle with the plane, convert it to the angle with the normal before substituting in BA cos theta.

Faraday's law states that the magnitude of induced emf in a circuit is equal to the rate of change of magnetic flux linked with the circuit. Mathematically, epsilon = - dPhi_B/dt for one turn and epsilon = -N dPhi_B/dt for N turns.

In written answers, mention both parts: changing magnetic flux is the cause, and induced emf is proportional to the rate of change of flux.

Lenz's law states that the direction of induced current is such that its magnetic effect opposes the change in magnetic flux that produces it.

For direction questions, first decide whether flux is increasing or decreasing, then choose the induced magnetic field that opposes that change.

Motional emf is the emf induced across a conductor moving through a magnetic field because charges in the conductor experience magnetic force. For a rod of length l moving with speed v perpendicular to a uniform magnetic field B, epsilon = Bvl.

Before substituting, check the geometry: B perpendicular to the plane of rails, rod length perpendicular to velocity, and rod moving steadily.

Self inductance is the property of a coil by which a changing current in it induces an emf in the same coil. Mutual inductance is the property by which a changing current in one coil induces an emf in a nearby coil.

For self inductance, look for changing current in the same coil. For mutual inductance, look for two coils and changing current in one causing emf in the other.

An AC generator is a device that converts mechanical energy into electrical energy by rotating a coil in a magnetic field, producing an alternating emf.

In diagram answers, label coil, magnetic poles, axle, slip rings, brushes, and external load. Also state the energy conversion and the reason for alternating emf.