Question

An electric dipole having each charge of magnitude $3\mu$ is placed in an electric field of intensity $4\times {10}^{4}N/C$. What is the length of the dipole, if the maximum torque acting on the dipole is $6\times {10}^{-3}N-C$

• A. $10mm$
• B. $25mm$
• C. $50mm$
• D. $75mm$

Answer 1

Answer: (B)

$25mm$

The Electric field is given as

$E=\frac{K{Q}^2}{R^2}$

Then the distance between the charges are as follows

$R^2=\frac{9\times {10}^9\times {\left(3\times {10}^{-6}\right)}^2}{4\times {10}^4}$

On solving we get the distance between the charges

$25mm$

Hence the dipole length is $25mm$