An electic dipole of length 2cm is placed with its axis making an angle 60 degree with respect to a uniform electric field of 105 N/C. If it experiences a torque of 13.856 Nm, calculate the- magnitude of the charge on the dipole & PE of the dipole.
The torque on an electric dipole placed in uniform electric field is given as
τ = qdE sinθ
or magnitude of charge will be
q = τ / dEsinθ
here
τ = 13.856 Nm
d = 2cm = 0.02m
E = 105 N/C
θ = 60 degrees
so,
q = 13.856 / (0.02 x 105 x sin60)
thus,
q = 8 mC
now,
The potential energy of an electric dipole placed in uniform electric field is given as
U = pEcosθ = (q2d)Ecosθ
so,
U = 8x10-3 x 2x0.02 x 105 x cos60
thus,
U = 16 J