Explain how an electromagnetic motor works?

A moving current in a magnetic field produces a force according to Fleming's Left Hand Rule. When a loop of wire with a current moving through it cuts magnetic field lines, movement is induced along the wire, perpendicular to both the direction of the current and magnetic field. This means that opposite sides of the loop move in opposite directions. The commutators connecting the wires to the power source ensure that the polarity of the current remains on the correct side of the magnetic field, i.e. it switches connecting ends of the wire every half revolution. This means that the motor will turn the same way indefinitely.