Question

If the dipole of moment $2.57 \times 10^{-17} cm$ is placed into an electric field of magnitude $3.0 \times 10^4 N / C$ such that the fields lines are aligned at $30^{\circ}$ with the line joining $P$ to the dipole, what torque acts on the dipole?

• A. $7.7 \times 10^{-13} Nm$
• B. $3.855 \times 10^{-13} Nm$
• C. $3.855 \times 10^{-15} Nm$
• D. $7.7 \times 10^{-15} Nm$

Answer 1

Answer: (B)

$\tau =\left(2.57 \times 10^{-17} Cm \right)\left(3.0 \times 10^4 \frac{ N }{ C }\right)\left(\frac{1}{2}\right) $
$=3.855 \times 10^{-13} Nm $