A-level Physics/Electrons, Waves and Photons/Magnetic effects of current

Right Hand Grip Rule

The most basic principle. Imagine your right hand gripping a pen while doing a "thumbs up"(it is vulgar in certain countries but this is for science). The thumb points to the direction of the conventional current while the other fingers points to the direction of the magnetif field lines(it circles around the direction of current).

Fleming's left hand rule

Use your thumb, first and second fingers to point at 90° to each other: like the corner of a box.
First finger: Field
seCond finger: Current
THumb: THrust

Formula

$F=B\,I\,L$

F is the force produced, measured in newtons. B is the magnetic field strength (flux density), measured in Tesla. I is the current that the magnetic field is acting on, measured in Amps. L is the length of the electrical wire, measured in metres.