Resistance in Conductors

How the Dimensions of a Conductor Affect its Resistance

The ability of any conductor in an electrical circuit to pass current is judged by its electrical RESISTANCE. Resistance is the ability to OPPOSE the flow of electric current. The greater the value of resistance of any conductor, the less current will flow. The resistance of a conductor depends mainly on three things;

The LENGTH of the conductor.

The CROSS SECTIONAL AREA of the conductor.

The MATERIAL of which the conductor is made.

Because the resistance is greater in longer conductors than in shorter ones, then;

RESISTANCE IS PROPORTIONAL TO LENGTH

Which is written as; R ∝ L (∝ means proportional to...)

Also, because resistance is less in conductors with a large cross sectional area;

RESISTANCE IS INVERSELY PROPORTIONAL TO CROSS SECTIONAL AREA

Which is written as; R ∝ 1/A (or R ∝ A^-1)

Dimensions of a conductor

When the conductor has a circular cross section the area of a circle can be found by using the formula;

π r² Where π = 3.142 and r is the radius of the circle.

If the cross section of the conductor is square or rectangular, the cross sectional area of the conductor can still be found by simply multiplying the width by the height. Most conductors, found in cables etc. are of course circular in cross section.