Question

Two equal charges $q$ are placed at a distance of $2a$ and a third charge $- 2q$ is placed at the midpoint. The potential energy of the system is

• A. $\frac{q^{2}}{8\pi\varepsilon_{0}a}$
• B. $\frac{6q^{2}}{8\pi\varepsilon_{0}a}$
• C. $- \frac{7q^{2}}{8\pi\varepsilon_{0}a}$
• D. $\frac{9q^{2}}{8\pi\varepsilon_{0}a}$

Answer 1

Answer: (C)

$- \frac{7q^{2}}{8\pi\varepsilon_{0}a}$

Answer 2

$U_{system(fudk;)} = \frac{1}{4\pi\varepsilon_{0}}\frac{(q)( - 2q)}{a} + \frac{1}{4\pi\varepsilon_{0}}\frac{( - 2q)(q)}{a} + \frac{1}{4\pi\varepsilon_{0}}\frac{(q)(q)}{2a}$

$U_{system(fudk;)} = - \frac{7q^{2}}{8\pi\varepsilon_{0}a}$