Question

An electric dipole of length 4 cm one place in its axis making an angle of 30 with a uniform electric field experience a track of 4 nm calculate magnitude of electric field and potential of the potential energy of the dipole is the dipole changes of 10 nano coulomb

Answer 1

length of the elctric dipole = 4cm=4×10-2 m

angle made with the elctric field-θ=60∘

Torque experienced by the dipole-τ = 43 Nm

charge on the dipole-q=±8nC = ±8×10-9 C

i) magnitude of Electric field-E

τ= pE sinθ = q × 2a × E sinθ

⇒ 43 = 8×10-9 × 4×10-2 × E × sin 60°

⇒ E = 43×232 ×10-11×3 = 14×1011 = 2.5 × 1010 NC-1

(ii) magnitude of potential energy of the dipole

U = -pE cos θ

= -q×2a×E cos θ

=-8×10-9×2×10-2×2.5×1010 cos 60°= - 2J.