An electric dipole is placed in a uniform electric field: (a) Show that no translatory force acts on it (b) Derive an expression for the torque acting on it. (c) Find work done in rotating the dipole through 180 degree
torque= qe x bc
= qe d sino (electric dipole p= qd ) (since bc= d sin o )
torque= PE sin o
An electric dipole will naturally have its dipole moment p aligned to the external electricfield E. the equilibrium configuration will have ?=0.When the dipole is not aligned, an external work W will have to be done on the dipole(from the external electric field) to bring it from the rest position to a given angle ?:UP = ?W = R?0 ?d?UP is the potential energy associated with the work done by the conservative elec-trostatic force, which causes the torque ? . The infinitesimal work done by the electrostaticforce is dW = ?d? = ?pE · sin(?)d?.? UP = pE · (? cos(?)|?0) = ?pE(·cos(?) ? ·cos(0)).