What is the electric potential from a charge of 3.0 x 10^-5 C at 15 cm and 65 cm? How much work must be done to carry a +2.3 x 10^-3 charge from 65 cm to 15 cm?

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Answer 1 · 2017-04-28T13:12:07

Potential #V# is:

#V = (k Q)/r#

#V(0.15) = ((9 xx 10^(9)) (3xx10^(-5)))/(0.15) approx 1.8MV#

#V(0.65) = ((9 xx 10^(9)) (3xx10^(-5)))/(0.65) approx 0.42MV#

The work required equals the change in potential energy #Delta U#, and #U = qV#

So:

#W = Delta U = q Delta V = 2.3xx10^(-3) cdot (1.8 - 0.42)cdot 10^6 = 3174 " J"#

Check the numbers yourself in yer calculator :)