But since a collapsing magnetic field is a moving magnetic field, it causes the electrons in the wire to move. The electrons are pushed by the magnetic field in the same direction that the battery used to be pushing them. We have also seen that as a magnetic field collapses it causes electrons to flow in the wire. The magnetic field and the electric field can thus be made to oscillate back and forth. As one collapses, it builds up the other.
Electric fields have a positive and a negative.
You can picture the two fields as the height and width of a balloon as you push down on it with your hand. As the height of the balloon collapses, the width of the balloon expands. The height is like the magnetic field, and the width is like the electric field. Notice that the two fields are always at right angles to one another. This is important to understanding polarization.