Question

what is responsible for making an axle spin in an electric motor?
o an outside power source attached to a magnet
o an outside power source attached directly to the axle
o an electric current passing through an armature that lies in a magnetic field
o a magnetic field inducing a current in an armature that lies in a magnetic field

Explanation:

In an electric motor, an electric current passing through an armature (coil of wire) placed in a magnetic field experiences a force due to the interaction between the magnetic field and the current - carrying conductor. This force causes the armature to rotate, which in turn rotates the axle.

Answer:

an electric current passing through an armature that lies in a magnetic field