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twinklestar10
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Homework Statement
An outer shell of charge +Q is insulated by a light thread. There is an inner sphere inside which is earthed. The radii of the outer shell and inner sphere are b and a respectively. What is the potential of a point which is at a distance r from the centre of the inner sphere, where
(i) r=b?
(ii) r=a?
Homework Equations
V at r = - [tex]\int charge/ (4\pi\epsilon r^{2})[/tex] from infinity to r
The Attempt at a Solution
Before answering the questions above, I find it difficult to calculate the amount of induced charge on the inner sphere... Because the outer shell having a charge of +Q doesn't mean that the inner shell must have an induced charge of -Q.
How can I find the amount of induced charge?
My teacher gave us some hints to solve this question:
the inner sphere is an open system as it is earthed
the amount of charge of the inner sphere can be calculated
Besides, I initially thought the potential must be 0 without calculation because it is earthed, but when I tried to do the integration (V = dE/ dr), I couldn't get it as 0 (maybe it's due to the problem that I couldn't find the amount of induced charge of the inner sphere)
Can anyone help me?
thanks!
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