Question

The amount of work has to be done in assembling three charged particles at the vertices of an equilateral triangle

• A. 434 J
• B. 334 J
• C. 234 J
• D. 134 J

Answer 1

Answer: (C)

Amount of work done is assembling the charges is equal to the net potential energy

So$,$ $P.E.=U_{12}+U_{13}+U_{23}$

$=\frac{K{q}_1{q}_2}{r_{12}}+\frac{K{q}_1{q}_3}{r_{13}}+\frac{K{q}_2{q}_3}{r_{23}}$

$=\frac{K\times {10}^{-10}}{r}\left[4\times 2+4\times 3+3\times 2\right]$

$=\frac{9\times {10}^9\times {10}^{-10}}{{10}^{-1}}\left(8+12+6\right)$

$=9\times 26=234J$

Hence,

option $\left(C\right)$ is correct answer.