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R = rho L / A

by oneplusone
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oneplusone
#1
Mar12-14, 07:35 PM
P: 127
When can you use this formula?
On page 13 it uses it here: http://web.mit.edu/8.02t/www/802TEAL...es/guide06.pdf

however my instructor said that you can only use it when you are using a wire and the current is flowing parallel to the axis.
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Simon Bridge
#2
Mar12-14, 09:45 PM
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That sounds right - it only works for a nice geometry.

consider a rectangular plate LxWxT dimensions (length x width x thickness)
the resistance between opposite corners won't be ##\rho L/WT##

Even if I attach the wires to the center of areas WxT, imagine W=T=1000m ... how does the current travel through the resistor then?


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