Factors that affect resistance of a wire?

Question

How do the following factors affect the resistance of a wire and how? Please explain well: cross-sectional area, magnetism and material.

Answer 1

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First, the total length of the wires will effect the amount of resistance. The longer the wire, the more resistance that there will be. There is a direct relationship between the amount of resistance encountered by charge and the length of wire it must traverse. After all, if resistance occurs as the result of collisions between charge carriers and the atoms of the wire, then there is likely to be more collisions in a longer wire. More collisions means more resistance.

Second, the cross-sectional area of the wires will effect the amount of resistance. Wider wires have a greater cross-sectional area. Water will flow through a wider pipe at a higher rate than it will flow through a narrow pipe; this can be attributed to the lower amount of resistance which is present in the wider pipe. In the same manner, the wider the wire, the less resistance that there will be to the flow of electric charge. When all other variables are the same, charge will flow at higher rates through wider wires with greater cross-sectional areas than through thinner wires.

A third variable which is known to effect the resistance to charge flow is the material that a wire is made of. Not all materials are created equal in terms of their conductive ability. Some materials are better conductors than others and offer less resistance to the flow of charge. Silver is one of the best conductors, but is never used in wires of household circuits due to its cost. Copper and aluminum are among the least expensive materials with suitable conducting ability to permit their use in wires of household circuits. The conducting ability of a material is often indicated by its resistivity. The resistivity of a material is dependent upon the material's electronic structure and its temperature. For most (but not all) materials, resistivity increases with increasing temperature. The table below lists resistivity values for various materials at temperatures of 20 degrees Celsius.

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Answer 2

Factors Affecting Resistance

Answer 3

The 2nd and 3rd discussions were good but didn't discuss magnetism. The 1st guy: an open circuit has infinite resistance.

Even a straight piece of wire has some self-inductance (or self-magnetism). One affect of inductance is that it opposes changes in current. So when you first apply a dc voltage across a wire and a dc current starts to flow, the self-inductance will resist the increase in current. It will appear to be because of higher resistance than expected. But the current will increase over a short time, and once it gets to a steady-state, the apparent resistance from the self-inductance is zero. This, self-inductance in a straight piece of wire, is a minor affect compared to components that presumably are in the circuit.

After the current reaches steady state, the self-inductance will try to oppose a decrease in current.

If the voltage and therefore the current are ac - alternating, this gets more complicated. The current is always trying to change. At the level of study I think you are, you should save this for later.

Answer 4

No dude, don't listen to that guy. The length of the wire: the longer the wire the more resistant. The thickness of the wire: the bigger the wire (in roundness: aka. Gage) the less resistant. And the type of material: silver is the best conductor but it tarnishes too easily. Gold is next best but is too expensive. So we use copper.

Answer 5

Sounds like you have the answer you need, electricity is not all that well understood. I would however, mention ambient temperature, and super cooled has little, or no resistance. Open circuits has no resistance, then how do you apply ohms law, in supercooled current?

Answer 6

Which of the following will not affect the resistance of a circuit?

Answer 7

Temperature, No.of turns, Material of the wire

Answer 8

r=pl/a
p-resistivity
l -length
a-cross sectional area
and temperature too