question_answer

Direction Q.26 to 30

When electric dipole is placed in uniform electric field, its two charges experience equal and opposites forces, which cancel each other and hence net force on electric dipole in uniform electric field is zero. However these forces are not collinear, so they give rise to some torque on the dipole. Since, net force on electric dipole in uniform electric field is zero, so no work is done in moving the electric dipole in uniform electric field. However some work is done in rotating the dipole against the torque acting on it.

Read the given passage carefully and give the answer of the following questions.

The dipole moment of a dipole in a uniform external field \[\overrightarrow{E}\]is \[\overrightarrow{P}\]. Then the torque \[\overrightarrow{\tau }\] acting on the dipole is:

A) \[\overrightarrow{\tau }=\overrightarrow{P}\times \overrightarrow{E}\]                    

B) \[\overrightarrow{\tau }=\overrightarrow{P}.\overrightarrow{E}\]

C) \[\overrightarrow{\tau }=2\left( \overrightarrow{P}\times \overrightarrow{E} \right)\]  

D) \[\overrightarrow{\tau }=\left( \overrightarrow{P}+\overrightarrow{E} \right)\]