Calculate the amount of work done by a uniform electric field of 200 `Vm^(-1)` on an electric dipole of length 0.05m and charge 40nC in order that the angle between the axis and the field is equal to `180^(@)`, what is the amount of torque required to maintain that position?

Explanation

`W=pE(1-costheta),p=(2l)q=(0.05)(40xx10^(-9))`
`therefore p=2xx10^(-9)Cm`
`therefore W=(2xx10^(-9))(200)(1-cos180^(@))=8xx10^(-7)J`
`tau=pEsintheta`
`tau=0" "because sin180^(@)=0`