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Electricity

Coulombs

Electrons are very small.
You can have a million electrons flowing around a circuit without noticing,
they won't light a lamp.

In physics, we take a very very large number of electrons
as 1 unit of charge - called a Coulomb.
Charge is given the symbol Q.

1 Coulomb = 6.2 x 10¹⁸ electrons.
(This is 6.2 million million million electrons).
Such a large number of electrons can do useful things
(like light a lamp).

Think of Coulombs as though they are busses,
taking a large number of electrons (like passengers)
from one side of the cell,
through all the components in the circuit,
and back to the other side of the cell.

This is called direct current.

We need to know the rate of Coulombs flowing around the circuit
(how many Coulombs per second),
and how much energy each Coulomb has
(how many Joules per Coulomb).

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Copyright © 2008 Dr. Colin France. All Rights Reserved.