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Currents and charge between spheres

  • Thread starter omri3012
  • Start date
  • #1
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Homework Statement



Consider two small conductive spheres in radius a and b located far from each other.
In t=0 "a" sphere charged with Q and "b" sphere neutral. We connect the spheres by wire with resistance R.
Find the charge on each sphere as a function of time.

Homework Equations



d[tex]\rho[/tex]/dt+divJ=0

I=dQ/dt

J=[tex]\sigma[/tex]E

R=[tex]\rho[/tex]*(L/A)

The Attempt at a Solution


I'm assumed that the change in charge in one sphere is the same in the other sphere with opposite sign. I tried to understand what is the relevant electric field and where should I calculate it (outside the sphere? Inside the wire?). I think that capacitance
Required here but the two spheres connected so it more like capacitor discharge… I'm lost.
 

Answers and Replies

  • #2
674
2
It is the same thing as connecting two capacitors to each other. So treat sphere 1 with capacitance C1, and the other with capacitance C2. And the charges will move from 1 to 2 until both capacitors have equal charge.
 

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