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Derive an expression for the work done in rotating an electric dipole of dipole moment 'p' in a uniform electric field 'E' from an orientation theta_1" to " theta_2. |
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Answer» SOLUTION :Consider an ELECTRIC dipole of dipole MOMENT `vecp` placed in a uniform electric field `vecE` oriented at an angle `theta` with the direction of electric field. The torque acting on the dipole is `tau = pE sin theta` Elementary work done in rotating the dipole further through a small angle `d theta` against the torque is `dW = tau d theta = pE sin theta d theta` `:.`TOTAL work done in rotating the dipole from orientation `theta_1 " to " theta_2` will be `W = underset(theta_1)overset(theta_2)int pE sin theta d theta= pE [ -costheta]_(theta_1)^(theta_2)=pE[cos theta_1 - costheta_2]` |
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