[soph_surfs]

Why is it that when the length of wire increases(acting as a variable resistor) , so does resistance???
I really don't get it.. help please?

[becky.fm]

Think about the fact that electons have got further to travel, because the length is increasing.. so it's harder for the electrons to pass through (there's more chance of them being blocked or whatever) = higher resistance.

Haha that's how i was taught at GCSE anyway

[TheMeister]

Look it up; this is for an ISA isn't it?

We've got the exam tomorrow as well.

[soph_surfs]

Cheers Naaa,, its GCSE

[elessar]

Mathematically, R=p*l/A, where p is resistivity
when length increases at constant area of cross section and resistivity(which depends on material's nature and temperature), as per the equation, R increases.

Physically, yeah, the length increase implies that electrons have to travel greater distance, therefore, more collisions occur, and hence, its more difficult. Since electron density(electrons per unit volume) is fixed in normal cases, for a material: the increase in area implies more electrons are now available for conduction, hence resistance decreases.(just in case you wanted to know about the effect of volume)

[teachercol]

Doubling the length of a wire is like adding two resistors in series

[hahaha...no]

http://phet.colorado.edu/sims/resist...a-wire_en.html