URGENT!!!How to DOOO (1 Viewer)

[Cade]

OMG I only have 2 days left to pass up my assignment and i still can't find the equation on how to find the diameter of 2 wires by comparing the resistance of the wires.....I do know that the equation linking the length and diameter is


R=p[L/A]
but how to prove it?? help meeeeee anyone

 

[alcalder]

Hi Cade, you are my first post. I saw your post and had to join up.

OK so

R=p(L/A)

If each resistor has the same length (say L=x) then:

and A=(pi)r^2 and r=d/2

R1 = p(x/(pi)r1^2) and R2 = p(x/(pi)r2^2)

OR

R1 = p(4x/(pi)d1^2) and R2 = p(4x/(pi)d2^2)

Therefore when you divide the two and cancel out stuff you get:

R1/R2 = (d2/d1)^2

Hope that helps.

 

[Cade]

wohooo thanks a lot man. really needed that.and to think tat the answer was juz starin rite in front of me.guess i shud start using my head more often. =P

 

[alcalder]

No problems, sometimes it just needs a nudge in the right direction.