# Current due to Potential Difference

## Homework Statement

Consider a rectangular block of metal of height A, width B, and length C , as shown in the figure. If a potential difference V is maintained between the two A X B faces of the block, a current Iab is observed to flow.

Find the current that flows if the same potential difference V is applied between the two B X C faces of the block

http://session.masteringphysics.com/problemAsset/1126202/2/Walker4e.ch21.Pr023.jpg

V=IR, R=rho(L/A)

## The Attempt at a Solution

V=IR, R=rho(L/A)

V=I*rho*(L/A)

Iab=(V)/(rho*(C/AB))

Ibc=(V)/(rho*(A/BC))

I thought this last equation was right, but apparently it isn't. When I entered it, it said that B, V, and rho had no impact upon the answer. I'm not really sure what to do now...

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By the way, it wants the answer in "terms of some or all of the variables A, B, C, and Iab."

the answer is Iab(C^2/A^2) due to the fact the voltages had to be set equal
IabR =IbcR
Iab(rhoL/A) =Ibc(RhoL/A)
Iab(RhoC/AB) = Ibc(RhoA/BC)
Rho's and B's cancel
IabC/A = IbcA/C
cross multiply
IabC^2=IbcA^2
Ibc =Iab(C^2/A^2)