To understand the operation of electric appliances, it is
useful to know some basic terminology of electricity and how it works. The flow
of electricity through wires is analogous to the flow of water through pipes.
As water is pumped through pipes, friction from the pipe walls and any restrictions
in the pipe offer resistance to the flow of water. If the pump is turned off,
water flow stops because of this resistance. When the pump is running, it provides
enough pressure to offset these resistances in the pipe and maintain the flow
of water through the system.
Like water through the pipes, electricity flows through wires.
This flow is called current and is expressed in amperes.
The wires and other devices in the electric circuit impede the flow of electricity.
This is called resistance and is expressed in ohms.
The voltage (also called electromotive force or EMF) is the relative
amount of electrical charge at one point in an electric circuit compared with
that at another point in the circuit. It is the "pump" which causes
a current flow through a continuous path between the two points. One volt is required
to cause one ampere of current to flow against a resistance of one ohm.