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Problem in Physics

One sphere with a radius of 1cm and another sphere with a radius of 2 cm are distanced with 1m appart, and are tied with the source of the electromotive force ε=3000 V. With what force these spheres interact?

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Andrew R. | PhD in Mathematical PhysicsPhD in Mathematical Physics
5.0 5.0 (13 lesson ratings) (13)
a=1cm, b=2cm,  d=1m,  ε=3000V. The situation describes a capacitor; assume 'plate' a has positive Q and b has -Q.
Approximate the potential at the surface of a to be: Va=kQ/a,
and at the surface of b: Vb=-kQ/b
Then ΔV= Va-Vb=kQ/a+kQ/b=kQ[(a+b)/ab]   (ΔV=ε=3000V)  then
Q=(ΔV/k)ab/(a+b)  (calculate Q numerically) and use
Coulumb's law  so that F≈kQ2/d2