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Positive electric charge Q is distributed uniformly throughout the volume of an insulating sphere with radius R.From the expression for E=kQ
Question
Positive electric charge Q is distributed uniformly throughout the volume of an insulating sphere with radius R.From the expression for E=kQ/r2 for r>R and E=kQr/R3 for r
Only need C & D. It asks for specfic points that I don’t know how to find. I just know the general shape of the graph.
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Physics
4 years
2021-07-15T02:51:45+00:00
2021-07-15T02:51:45+00:00 1 Answers
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Answers ( )
Answer:
Vb = k Q / r r <R
Vb = k q / R³ (R² – r²) r >R
Explanation:
The electic potential is defined by
ΔV = – ∫ E .ds
We calculate the potential in the line of the electric pipe, therefore the scalar product reduces the algebraic product
VB – VA = – ∫ E dr
Let’s substitute every equation they give us and we find out
r> R
Va = – ∫ (k Q / r²) dr
-Va = – k Q (- 1 / r)
We evaluate with it Va = 0 for r = infinity
Vb = k Q / r r <R
We perform the calculation of the power with the expression of the electric field that they give us
Vb = – int (kQ / R3 r) dr
We integrate and evaluate from the starting point r = R to the final point r <R
Vb = ∫kq / R³ r dr
Vb = k q / R³ (R² – r²)
This is the electric field in the whole space, the places of interest are r = 0, r = R and r = infinity