Question

An electric dipole moment $\overrightarrow{P}=\left(2.0\hat{i}+3.0\hat{j}\right)\mu C.$ .m is placed in a uniform electric
field$\overrightarrow{E}=\left(3.0\hat{i}+2.0\hat{k}\right)\times {10}^5$

• A. The torque that $\overrightarrow{E}$ exert on $\overrightarrow{P}$ is $\left(0.6\hat{i}+0.4\hat{j}-0.9\hat{k}\right)Nm$
• B. The potential energy of the dipole is -0.6J.
• C. The potential energy of the dipole is 0.6J.
• D. None of these

Answer 1

The correct option is C The potential energy of the dipole is 0.6J.

$\overline{P}=(2.0\hat{i}+3.0\hat{j})\mu C$

$\overline{E}=(3.0\hat{i}+2.0\hat{k})\times {10}^5$

$E=\rho E.\cos \theta$

$=(2.0\hat{i}+3.0\hat{j})(3.0\hat{i}+2.0\hat{k})\times {10}^5$

$=0.6J$