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Resistance of a wire - electrons and ions - will somebody please help me?!!!!!

Hi,

I am doing my plan for my coursework on the resistance of a wire with relation to length. I have predicted that the they are in direct proportion e.g. when one doubles so does the other. Yet when I am explaining my reasoning for this I have gotten a little confused! I have said that by doubling the length of a piece of wire, the amount of lattice ions with which the electrons collide also doubles. This means that the amount of collisions doubles and therefore so does the resistance. Is this correct? I have had a look through the threads on this but I'm not sure whether by doubling the length of a piece of wire you also double the amount of electrons or lattice ions, or both. Would you be able to clear this up for me? I am going to keep current constant in my experiment if this makes any difference.

Thanks for your help.

Reply 1

Hanratarsed

I think if you double the legnth of the wire, then you double the number of lattice ions, so double the number of collisions. Although there will be twice as many electrons within the wire, this wont matter because its the rate of flow of the electrons that matters - each individual electron will have (on average) twice as many collisions, and so the wire will have twice the resistance.

Luke

Reply 2