Three point charges 3nC, 6nC and 6nC are placed at the corners of an equilateral triangle of side 0.1 m. The potential energy of the system is

Options

A. `9910 J`
B. `8.91 muJ`
C. `99100 J`
D. `89100 J`

Answer

B

Explanation

Given, `q_(1)=3nC=3xx10^(-9)C`
`q_(2)=6nC=6xx10^(-9)C`
`q_(3)=9nC=9xx10^(-9)C`
`r_(12)=r_(23)=r_(13)=0.1m`
Now, potential energy of the system.
`U=(1)/(4pi epsilon_(0))[(q_(1)q_(2))/(r_(1)r_(2))+(q_(2)q_(2))/(r_(23))+(q_(1)q_(3))/(r_(13))]`
`=(9xx10^(9))/(0.1)[3xx6+6xx9+3xx9]xx10^(-18)`
`=8910xx10^(-9)J=8.091muJ`