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Magnetic force

A charge moving in a magnetic field feels a force perpendicular to both its velocity and the field, given by the right-hand rule. A current-carrying conductor in a magnetic field feels a similar force, because the current consists of many moving charges.

F = qvB\sin\theta

force on a charge in a magnetic field

F = BIL\sin\theta

force on a current-carrying conductor

Symbols

$B$	magnetic flux density	T
$v$	speed	m/s
$I$	current	A
$L$	length of the conductor	m

Example

A conductor with $L = 0.50$ m carries $I = 5.0$ A perpendicular to a field $B = 0.80$ T. The force is $F = 0.80\cdot 5.0\cdot 0.50 = 2.0$ N.

The magnetic force is always perpendicular to the velocity, so it never does work – it only changes the direction of motion.

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