Question

An electric dipole consists of two opposite charges of magnitude $1\mu C$ separated by a distance of 2cm. The dipole is placed in an electric field ${10}^{-5}V{m}^{-1}$. The maximum torque that the field exerts on the dipole is:

• A. ${10}^{-3}Nm$
• B. $2\times {10}^{-13}Nm$
• C. $3\times {10}^{-3}Nm$
• D. $4\times {10}^{-3}Nm$

Answer 1

Answer: (B)

$2\times {10}^{-13}Nm$

The torque experienced by a dipole in an electric field E is $\overrightarrow{p}\times \overrightarrow{E}$

Maximum torque $=pE=qaE={10}^{-6}\times 0.02\times {10}^{-5}=2\times {10}^{-13}Nm$