I felt a little foolish this morning when asked to explain the sparks that
happen when momentarily touching two jumper cables together. The sparks
don't seem to happen unless there is contact and they go shooting off from
the two terminals.
I want to say that the conditions for the sparks happen just before contact
and again just after when the field is strong enough even with 12 V
potential. However, I could not convince myself of the proper explanation
and sadly the student left without a definitive response.