10 `mu`C charge Is placed on each vertex of equilateral triangle of 10 cm side. Electric potential energy of system is ......

Options

A. 100 J
B. 27 J
C. zero
D. infinte

Answer

B

Explanation

Electric potential energy of system
`U=(kq_(1)q_(2))/(a) +(kq_(2)q_(3))/(a) +(kq_(1)q_(3))/(a)`
`= (k)/(q)[q_(1)q_(2)+q_(2)q(3)+q_(1)q_(3)]`
`=(9xx10^(9))/(10xx10^(-2))[100xx10^(-12)+100xx10^(-12)+100xx1-0^(-12)]`
`U = 9xx10^(10)[3xx10^(-10)]`
`:. U = 27 J`