Lesson 1/Learning Event 1
When there is a surplus of electrons at one end of a wire and a shortage of electrons at the other
end, electrons will flow from the surplus to the shortage. Since a surplus of electrons is a negative
charge and the shortage a positive charge, electric current then flows from negative to positive.
FIGURE 3. ELECTRON MOTION.
When an electron leaves the negative source, this same electron does not just speed through the
wire. Instead it strikes another electron and knocks it loose from its atom. This loosened electron
then strikes another electron knocking it free. As one electron knocks another loose, it replaces the
one it knocked out. This occurs as a chain reaction throughout the entire length of the wire.
To illustrate this action, imagine that you have a pipe filled with marbles from end to end. If you
push a marble in one end of the pipe one marble will pop out the opposite end. As soon as the
marble presses on the column of marbles, its movement is transmitted all the way through the pipe.
The pipe is comparable to a wire and the marbles to electrons.
We know that it takes mechanical energy to crank an engine, yet it is done by supplying electrical
energy to a starter motor from the vehicle battery. Also, we know that by using mechanical energy
connecting link between mechanical energy and electrical energy. To understand why it is, we must
first learn some basic facts about magnetism.