How the length of a wire affects the resistance
Aim: To investigate how the electrical resistance of a wire changes in relationship to its length.
Variables :
1.Temperature: When electrons pass through a wire, they give off some of their energy to the atoms, the atoms in the wire will start to vibrate because of their increase in energy. This causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance.
2.Wire length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this the length increase should be proportional to the resistance increase.
3.Cross Section: As the cross-sectional area increases the resistance decreases.
4.Metal Type: Copper is a good conductor and is used for connecting wires..
Hypothesis
I predict that if the length increases then the resistance will also increase in proportion to the length. I think this because the longer the wire the more atoms and so the more likely the electrons are going to collide with the atoms. Therefore, if the length is doubled the resistance should also double. This is because if the length is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance. If this Experiment were set in a more controlled environment the Length of the wire would be proportional to the resistance. If the length of the wire is only half the length of another wire of the same type of wire, there should be half the number of collisions between the electrons and the atoms.
If the wire is twice as long, there should be twice the number of atoms, resulting in twice as many collisions and a predicted doubling of the resistance.
