question_answer

Two point dipoles of dipole moment \[{{\vec{p}}_{1}}\]and \[{{\vec{p}}_{2}}\]are at a distance x from each other and \[{{\vec{p}}_{1}}||{{\vec{p}}_{2}}.\] The force between the dipoles is:

A) \[\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{4{{p}_{1}}{{p}_{2}}}{{{x}^{4}}}\]

B) \[\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{3{{p}_{1}}{{p}_{2}}}{{{x}^{4}}}\]

C) \[\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{6{{p}_{1}}{{p}_{2}}}{{{x}^{4}}}\]

D) \[\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{8{{p}_{1}}{{p}_{2}}}{{{x}^{4}}}\,\]

Correct Answer: B

Solution :

[b] Force of interaction \[F=\frac{1}{4\pi {{\varepsilon }_{0}}}.\frac{3{{p}_{1}}{{p}_{2}}}{{{x}^{4}}}\]