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Two charged spheres are held a distance, r, apart. One sphere has a charge of +4µC,...

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sami112233 | Student, Undergraduate | (Level 2) eNoter

Posted June 26, 2013 at 3:15 PM via web

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Two charged spheres are held a distance, r, apart. One sphere has a charge of +4µC, and the other sphere has a
charge of +8µC. Compare the force of the +4µC sphere on the +8µC sphere with the force of the +8µC sphere
on the +4µC sphere.

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llltkl | College Teacher | (Level 3) Valedictorian

Posted June 26, 2013 at 3:53 PM (Answer #1)

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Being of the same sign (both +ve), the two charges repel one another, and the magnitude of this force is given by Coulomb’s law:

`F = 1/(4piepsilon_o)(q_1*q_2)/r^2`

`=1/(4*pi*8.85419*10^(-12))(4*10^-6*8*10^-6)/ r^2 N`

`= 0.2877/r^2 N`

Each charge exerts a force of repulsion of `0.2877/r^2 N` on the other charge (recall Newton’s third law) .

Therefore, the force of repulsion exerted by the +4µC sphere on the +8µC sphere and the force of repulsion exerted by the +8µC sphere on the +4µC sphere are exactly the same.

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