# Help: deriving formula for a uniform resistive sheet current

Discussion in 'General Electronics Chat' started by gotumal, Jun 25, 2009.

1. ### gotumal Thread Starter Active Member

Mar 24, 2008
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0

I have a plane resistive square sheet of area 10 X 10 mm. The sheet is uniform with the gradiant of 1k per mm. I have four output terminals at four conrners of the square.

With the co-ordinates (0,0) at the centre of my sheet, I inject a current with pointed probe of known value (say 10µA) at a point with co-ordinates (x,y). This current would get distributed accordingly. For instance, if the injection is at centre, current at four terminals would be 2.5µA each.

After struggling for one hour, I have posted this thread to get the help to derive the relation between four output currents, co-ordinates and input current.

Thanks in advance, if you could help me.

Jan 11, 2009
818
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3. ### gotumal Thread Starter Active Member

Mar 24, 2008
99
0
Thanks russ_hensel,

But I want an euation which would give me output currents. I am near to the solution, I think.

If the injecting co-ordinat is (5,5), my that corner current would be equal to total current and all other currents 0. similar would be the case for (-5,5), (-5,-5) and (5,-5). As I said earlier, at centre, all current would equally devide. I need to consider distance between each corners and total current to get four terminal current values.

But still I am not able to get right equation.

P.S.: When you are busy with 6-sigma, kaisen, FMEA meetings it's painfull to realise that you have forgotten your basics!