Fleming’s left hand rule
The direction of a motor effect force can be found using Fleming’s left hand rule.
Hold your thumb, forefinger and second finger at right angles to each other:
- the forefinger is pointed in the direction of the magnetic field lines - from north to south;
- the second finger is pointed in the direction the current flows;
- the thumb shows the direction of the force on the conductor carrying the current.
In which direction will this wire feel a force?
With forefinger (magnetic field) pointing from N to S (i.e. left to right), and second finger (current) pointing down, your left thumb (force) will point towards you.
This is the direction in which the force acts.