Motora

Meet Motora, a current-carrying wire who gets pushed sideways by a magnetic field.

Charges moving through a magnetic field feel a force at right angles to both their motion and the field. A wire carrying current is full of moving charges, so the whole wire is pushed. For a straight wire of length L at right angles to a uniform field B, the force is F = BIL. Reverse the current or the field and the push reverses.

Example: a 0.1 m wire carrying 5 amperes in a 0.5 tesla field feels 0.5 × 5 × 0.1 = 0.25 newtons.

In a coil inside a magnet, the current flows one way on one side and the other way on the opposite side, so the two sides are pushed in opposite directions and the coil turns. A commutator or electronic switching keeps it turning in the same direction. That is how electric motors work, from fans to electric cars. Loudspeakers use the same force to move a cone.

F = BIL applies when the wire is perpendicular to the field. At an angle θ, the force is BIL sin θ, and a wire parallel to the field feels nothing.