Question

A system of three charges are placed as shown in the figure:
lf D >> d, the potential energy of the system is best given by:
(A) 1/4πε₀ [(—q²/d) — (qQd/D²)] (B) 1/4πε₀ [(—q²/d) — (qQd/2D²)]
(C) 1/4πε₀ [(—q²/d) + (2qQd/D²)] (D) 1/4πε₀ [(+q²/d) — (qQd/D²)]

Answer 1

The potential energy of the system is best given by U(total) = 1/4πε₀ [(+q²/d) — (qQd/D²)]

Option (D) is correct.

Explanation:

U(total) = U self of dipole + U interaction

U(total) = - Kq^2 / d -( KQ/D^2) qd

U(total) = - k [ - q^2 /d + qQd / D^2]

Thus the potential energy of the system is best given by U(total) = - k [ - q^2 /d + qQd / D^2]

Or

1/4πε₀ [(+q²/d) — (qQd/D²)]