Magnetic Fields and Electromagnetic Induction (Chapter 24 + 25)

Line of Force

The line along which the north pole of a magnet would move in a magnetic field.

The Motor Effect

A current-carrying wire at a non-zero angle to an external magnetic field’s line of force experiences a force.

Fleming’s Left-Hand Rule

A rule which relates the direction of the magnetic field, current in a wire, and the resultant motion of that wire.

Second Finger

Current.

First Finger

Field

Thumb

Motion

Magnetic Flux Density

The force per unit length, per unit current, on a current-carrying conductor at a right angle to the magnetic field lines.

Lenz’s Law

The direction of an induced current is always opposite to the change that caused it.

Faraday’s Law

That the induced EMF by the movement of a conductor through a magnetic field is euqal to the negative of the rate of change of the flux linkage.

Magnetic Flux

The magnetic flux density of a field multiplied by the perpendicular area of an object within the field.

Weber

The units for magnetic flux, equal to Tesla Metres Squared.

Magentic Flux Linkage

The magnetic flux on a coil multiplied by the number of turns on the coil.

Electromagnetic Induction

When an EMF is induced in a wire because it is moved in a magnetic field, only creates a current if the wire is attached to a circuit.