If the wire has a circular cross-section - the usual case - use the formula for the circle: pi x radius squared.
If the diameter doubles (x2), the cross-sectional area quadruples (x4).
Imagine the wire is straight, now cut through at right angle to the centre line, the exposed surface is the cross sectional area, on a round wire it = pi * radius2 (area of a circle)
Other things being equal, more cross-sectional area will cause less resistance.
It quadruples.
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When it is on the cross-sectional area it is inversely proportional to the wire,otherwise it is directly proportional to the wire.
If you slice a wire cleanly and then look at the cut end, you see a little circle at the end. The area of that circle is the "cross-sectional area" of the wire. The larger that area is, the lower the DC resistance of the wire is.
The resistance is based on the cross sectional area. It is conceivable that you could bend a wire in such a way as to affect the cross sectional area, but unlikely.
If the diameter doubles (x2), the cross-sectional area quadruples (x4).
Imagine the wire is straight, now cut through at right angle to the centre line, the exposed surface is the cross sectional area, on a round wire it = pi * radius2 (area of a circle)
Other things being equal, more cross-sectional area will cause less resistance.
Since resistance is inversely-proportional to cross sectional area, the lower the cross-sectional area, the higher the resistance. So ALL types of wire exhibit this behaviour!
It quadruples.
0.0031
Temperature, Length of wire, Area of the cross-section of wire and nature of the material.
Assuming the wire follows Ohm's Law, the resistance of a wire is directly proportional to its length therefore doubling the length will double the resistance of the wire. However when the length of the wire is doubled, its cross-sectional area is halved. ( I'm assuming the volume of the wire remains constant and of course that the wire is a cylinder.) As resistance is inversely proportional to the cross-sectional area, halving the area leads to doubling the resistance. The combined effect of doubling the length and halving the cross-sectional area is that the original resistance of the wire has been quadrupled.
Resistance is inversely-proportional to the cross-sectional area of a conductor. For example, doubling its cross-sectional area will halve its resistance, while halving its cross-sectional area will double its resistance.Since the cross-sectional area of a circular-section conductor is proportional to the square of its radius, doubling that radius will reduce its resistance by one quarter, while halving its radius will quadruple its resistance.