Question

An electric dipole of length $10cm$ having a charge $(+/-)6\times {10}^{-3}C$ placed at ${30}^o$ with respect to a uniform electric field experiences a torque of magnitude $6\sqrt{3}N-m$. Calculate the potential energy of the dipole.

• A. $0J$
• B. $0.18J$
• C. $-18J$
• D. None of these

Answer 1

Answer: (C)

$-18J$

$U=-pEcos\theta$

$\tau =pEsin\theta$

From above equations,

$U=-\tau \times cot\theta$

$U=-6\sqrt{3}\times \sqrt{3}$

$U=-18J$