JEE Advanced2020PhysicsWork, Power and EnergyActual
A point charge q of mass m is suspended vertically by a string of length l . A point dipole of dipole moment p → is now brought towards q from infinity so that the charge moves away. The final equilibrium position of the system including the direction of the dipole, the angles and distances is shown in the figure below. If the work done in bringing the dipole to this position is N × ( m g h ) , where g is the acceler
Correct answer
0
Step-by-step solution
W = q V + m g h = q k p x 2 + m g h . . . 1 For equilibrium q E sin β = m g sin 90 - α 2 q E sin ( 180 - α ) = m g cos α 2 ; q E sin α = m g cos α 2 9 E 2 sin α 2 cos α 2 = m g cos α 2 ; q E = 2 mg sin α 2 q k p x 2 = m g x sin ( α 2 ) = m g sin α 2 · h sin α 2 q k p x 2 = m g h . . . 2 From (1) and (2) W = 2 m g h x = 2