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# Physics Resistance help watch

1. Hey! im attempting some of the "harder" questions my teacher has set for me. i have done all but one and this one has completely stumped me. im wondering if someone could point me in the right direction. I posted in physics first but a responder suggested i see if the mathematicians could solve this. This is all the information i have to go on

Question:

"A hollow sphere made of graphite (ρ=25×10-5Ωm) has an outside radius of 100mm and an inside radius of 99mm

Calculate a rough value for the resistance of this sphere when connected at opposite poles."
2. (Original post by (1)Quantum)
Hey! im attempting some of the "harder" questions my teacher has set for me. i have done all but one and this one has completely stumped me. im wondering if someone could point me in the right direction. I posted in physics first but a responder suggested i see if the mathematicians could solve this. This is all the information i have to go on

Question:

"A hollow sphere made of graphite (ρ=25×10-5Ωm) has an outside radius of 100mm and an inside radius of 99mm

Calculate a rough value for the resistance of this sphere when connected at opposite poles."
Model the sphere as a set of N rectangular strips curved into the shape of the graphite shell. They are prisms so it's easy to calculate their resistance from the resistivity. Then note that they are arranged in parallel, when measuring resistance between the poles.

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