Length,current, cross sectional area and turns of wire if any and permeability of wire

Factors affecting the resistance of a conductor in the shape of a wire:

1. Length of the wire:
The resistance of a wire is directly proportional to its length. As the length of the wire increases, the resistance also increases. This is because the longer the wire, the more collisions there will be between the moving electrons and the atoms of the wire, resulting in a higher resistance.

2. Cross-sectional area of the wire:
The resistance of a wire is inversely proportional to its cross-sectional area. A thicker wire has more space for the electrons to flow, reducing the number of collisions and thus lowering the resistance. Therefore, a wire with a larger cross-sectional area will have a lower resistance compared to a wire with a smaller area.

3. Material of the wire:
Different materials have different resistivities, which is a measure of how much a material opposes the flow of electric current. Materials with high resistivities, such as nichrome or tungsten, have higher resistance values compared to materials with low resistivities, such as copper or silver. Therefore, the resistance of a wire depends on the type of material it is made of.

4. Temperature:
The resistance of a wire generally increases with an increase in temperature. This is because as the temperature rises, the atoms or ions of the wire vibrate more vigorously, leading to more frequent collisions with the moving electrons and an overall increase in resistance. However, there are some exceptions, such as the negative temperature coefficient of resistance exhibited by certain materials like thermistors.

5. Presence of impurities or foreign substances:
Impurities or foreign substances in the wire can disrupt the flow of electrons and increase resistance. These impurities can scatter the electrons, causing them to collide more frequently and leading to a higher resistance. Pure metals, such as copper or silver, have fewer impurities and therefore lower resistance compared to alloys or impure metals.

6. Temperature coefficient of resistance:
Each material has a specific temperature coefficient of resistance, which determines how the resistance changes with temperature. Some materials have a positive temperature coefficient, meaning their resistance increases with temperature, while others have a negative temperature coefficient, where the resistance decreases with temperature.

In conclusion, the resistance of a conductor in the shape of a wire depends on factors such as its length, cross-sectional area, material, temperature, presence of impurities, and the temperature coefficient of resistance of the material. Understanding these factors helps in designing and selecting appropriate wires for various electrical applications.