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The Resistance of Wires - Theory.

When we see a circuit with its components, we usually
assume that the wires that connect the components and
complete the circuit have a resistance of zero ohms.
This is often a good approximation, since the resistance
of the wires in the circuit is much smaller than the
resistance of a component such as a lamp or a motor.
However, all wires have a small electrical resistance.

What is the Cause of Electrical Resistance?

When electrons move through the wire, some electrons
collide with the ions of the material in the wire.
It is these collisions that cause electrical resistance.
With each collision, some energy is lost to the wire
as heat. This explains the heating effect of current.

When the current through a wire increases, the number
of collisions between the electrons and the ions
and the wire gets hotter. See how a fuse works.

Wires (and resistors) transfer electrical energy into
heat energy. The heat can be used to make a lamp work.

There are other factors that affect the resistance of wires.

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