Question

There are 3 charges of +1C, +2C and +3C at the vertices of an equilateral triangle of length 2m. What is the Potential energy of the system assuming potential energy at infinite separation to be zero?

• A. $4.95\times {10}^{10}J$
• B. $5.95\times {10}^{10}J$
• C. $2.95\times {10}^{10}J$
• D. $3.95\times {10}^{10}J$

Answer 1

The correct option is A

$4.95\times {10}^{10}J$

The answer is simply the sum of potential energy between all pairs of particles.
P.E = kq1q2/r12 + kq2q3/r23 + kq3q1/r31
$P.E=\frac{k}{2}(2\times 3+3\times 1+1\times 2)P.E=9\times {10}^9\times \frac{11}{2}P.E=4.95\times {10}^{10}J$