A) \[\sqrt{2}\,pE\]
B) \[\frac{pE}{2}\]
C) 2pE
D) pE
Correct Answer: D
Solution :
When an electric dipole is placed in an electric field \[\vec{E}\], a torque \[\vec{\tau }\] = \[\vec{p}\] x \[\vec{E}\] acts on it. This torque tries to rotate the dipole through an angle. If the dipole is rotated from an angle \[{{\theta }_{1}}\] to \[{{\theta }_{2}}\] then work done by external force is given by \[W=pE(\cos {{\theta }_{1}}-\cos {{\theta }_{2}})\] ...(i) putting \[{{\theta }_{1}}={{0}^{o}},\,\,{{\theta }_{2}}={{90}^{o}}\] in the Eq. (i), we get \[W=pE(\cos {{0}^{o}}-\cos {{90}^{o}})\] \[=pE\,\,(1-0)\] \[=pE\]
You need to login to perform this action.
You will be redirected in
3 sec
