CBSE - XII Science - Physics - Moving Charges and Magnetism
Why is the potential energy min. for an electric dipole when torque is max. in a const. electric fie
In case of a diploe,
charge q1 = +q and charge q2 = -q, if the external field be along th x direction, and the origin be at the center of the dipole, then the potential energy of the dipole is:
qv(r1) - qv(r2)-q2/(4π∈o2a)
The potential differnce between q1 and q2 is the work done in moving a unit positive charge against field..
v(r1) - v(r2) = - E. 2 a cos q
Negative potential indicates the decrease in potential in the direction of field.
Dipole has minimum potential energy when alligned with the field and a dipole in a uniform field experiences a torque. Thus, if dipole can fritter away its potential energy, torque will allign the dipole in the direction of the external field therby making its potential to a minimum .
Hope this helped.
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