Three charges ` 0.1` coulomb each are placed on the corners of an equilateral triangle of side `1 m`. If the energy is supplied to this system at the rate of ` 1 kW` how much time would be required to move one to the charges on to the midpoint of the line joining the two ?

Explanation

`U_(1) = (1)/(4 pi in_(0)) [(0.1 xx 0.1)/(1) xx 3]`
`= 9 xx 10^(9) xx 3 xx 10^(-2) = 27 xx 10^(7) J`
`U_(2) = (1)/(4 pi in_(0)) [ (0.1 xx 0.1)/(0.5) xx 2 + (0.1 xx 0.1)/(1)]`
`= 9 xx 10^(9) xx 0.05 = 45 xx 10^(7) J`
`W_(1 rarr 2) = U_(2) - U_(1) = 18 xx 10^(7) J`
`P = (W)/(t)`
`t = (W)/(P) = (18 xx 10^(7))/(10^(3)) s = 50 hr`
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