3  Potential energy of a dipole in an external field
Consider a dipole with charges q1 = +q and q2 = –q placed in a uniform
electric field E, as shown in Fig 2 16 As seen in the last chapter, in a uniform electric field,
the dipole experiences no net force; but experiences a
torque t t t t t given by
t = 
t = 
t = 
t = 
t = p × E
(2