gcsescience.com                                       47                                       gcsescience.com

Electricity

The Resistance of Wires - Thickness.

Does the Resistance of a Wire depend on its Thickness?

The resistance of a wire changes if its thickness changes.
The thinner the wire, the bigger its resistance.
You must use thick wire to carry a large current,
or the wire gets too hot and melts (like a fuse).

The relationship between resistance and thickness is
not straightforward. Halving the thickness of a wire does
not double the resistance. Compare this with the
relationship between a wire's resistance and its length.

What is the Relationship between the
Cross-Sectional Area and the Resistance of a Wire?

The cross-sectional area is what you get when
you cut through the wire, at right angles to its length,
and look at the cut surface. If the wire is round,
the cross-section is a flat circle and the area is πr².

The cross-sectional area of a wire is
inversely proportional to the resistance of the wire.
Doubling the area will halve the resistance.

     Links      Electricity      Mains      Revision Questions