Q.

An electric dipole of mass m, charge q, and length l is placed in a uniform electric field E=E0i^. When the dipole is rotated slightly from its equilibrium position and released, the time period of its oscillations will be:          [2025]

1 12π2mlqE0  
2 2πmlqE0  
3 12πml2qE0  
4 2πml2qE0  

Ans.

(4)

τ=PE0 sin θ

If θ is small, τ=(PE0)θ

       I=m(l2)2·2=ml22

       T=2πml22·PE0=2πml22·qIE0

 T=2πml2qE0