In a flashlight there are two batteries, stacked end-to-end, with the bump-end of one against the indented end of the next. This way of connecting batteries is called "putting the batteries in series."
Compare the behavior of the light bulb when connected
to one, two, or three batteries this way.
--Do not try more than three batteries, unless you are
going to pay for a new light bulb!
Copyright 2003 J. P. Straley and S. A. Shafer