Question

Three point charges q1, q2 and q3, each of magnitude 200 μC, are placed atthe corners A, B and C respectively of an equilateral triangle. The length ofthe side is 10cm. Calculate the potential energy of the system.

Answer 1

potential energy of the system of three charges is given as, $U=\frac{kq_1q_2}{r}+\frac{kq_2q_3}{r}+\frac{kq_3q_1}{r}$

given, $q_1=q_2=q_3=200\mu C=2\times10^{-4}C$

r = 10cm = 0.1 m

so, U = {9 × 10^9 × (2 × 10^-4)²}/(0.1) + {9 × 10^9 × (2 × 10^-4)²}/(0.1) + {9 × 10^9 × (2 × 10^-4)²}/(0.1)

= {3 × 9 × 10^9 × (2 × 10^-4)²}/(0.1)

= 27 × 10^9 × 4 × 10^-8 × 10

= 108 × 100

= 10800 J

hence, potential energy of the system is 10800J