Question

An electric dipole, when held at $60^{\circ}$ with respect to a uniform electric field of $10^{7} NC ^{-1}$ experience a torque of $12 \times 10^{-20} N - m .$ What is the value of dipole moment?

• A. $1.4 \times 10^{-26} C - m$
• B. $8 \times 10^{-27} C - m$
• C. $3 \times 10^{-26} C - m$
• D. $1.4 \times 10^{-27} C - m$

Answer 1

Answer: (A)

$\tau= pE \sin \theta$
$12 \times 10^{-20}= p \times 10^{7} \times \frac{\sqrt{3}}{2}$
$\therefore p =\frac{2 \times 12 \times 10^{-20}}{10^{7} \times 1.73}$
$=1.4 \times 10^{-26} C - m$