When a conductor carrying a current is placed inside a magnetic field, it experiences a force. This is known as the motor effect. The direction of the force is at right angles to both the field and the current and can be described by Fleming's Left Hand Rule.
Experiments indicate the force
is proportional to
-
the magnitude of the magnetic force
-
the magnitude of the current
-
The length of the conductor
in the magnetic field. -
The sine of the angle between the current and the magnetic field.
The magnitude of the force is given by
Technically the force per unit length,
in the diagram below is equal to the cross product of
and
It must be noted that if
so that the current and the field are parallel or if
so that current and field are anti – parallel,
and the magnetic force is zero. If
or 270 then current and field are at right angles and
and the force is maximum in magnitude.