Question

A +1.0 nC charge is at x = 0 cm, a -1.0 nC charge is at x = 1.0 cm and a 4.0 nC at x= 2 cm. What is the electric potential energy of the group of charges ?

Answer 1

- 2.7 x 10^-6 J

Step-by-step explanation:

q1 = 1 nC at x = 0 cm

q2 = - 1 nC at x = 1 cm

q3 = 4 nC at x = 2 cm

The formula for the potential energy between the two charges is given by

`U=(Kq_(1)q_(2))/(r)`

where r be the distance between the two charges

By use of superposition principle, the total energy of the system is given by

`U = U_(1,2)+U_(2,3)+U_(3,1)`

`U=(Kq_(1)q_(2))/(0.01)+(Kq_(2)q_(3))/(0.01)+(Kq_(3)q_(1))/(0.02)`

`U=-\frac{9*10^(9)* 1*10^(-9)* 1*10^(-9)}}{0.01}-\frac{9*10^(9)* 1*10^(-9)* 4*10^(-9)}}{0.01}+-\frac{9*10^(9)* 1*10^(-9)* 4*10^(-9)}}{0.02}`

U = - 2.7 x 10^-6 J