An electric dipole is placed at an angle of 30° with an electric field of intensity 2 × 105 NC -1. It experiences a torque equal to 4 Nm. Calculate the charge on the dipole if the dipole length is 2 cm.

Question

An electric dipole is placed at an angle of 30° with an electric field of intensity 2 × 105 NC -1. It experiences a torque equal to 4 Nm. Calculate the charge on the dipole if the dipole length is 2 cm. (A) 8 mC (B) 4 mC (C) 8 μ C (D) 2 mC

Tardigrade Admin · Accepted Answer

Torque on dipole is τ= pE sin θ τ=q × 2 E l sin θ ⇒ q=(τ/2 E l sin θ) ⇒ q=(4/2 × 2 × 105 × 2 × 10-2 × sin 30°) or q=2 mC

Q. An electric dipole is placed at an angle of $3 0^{\circ}$ with an electric field of intensity $2 \times 1 0^{5} N C^{- 1}$ . It experiences a torque equal to $4 N m$ . Calculate the charge on the dipole if the dipole length is $2 c m$ .

$8 m C$

$4 m C$

$8 μ C$

$2 m C$

Torque on dipole is $τ = pE sin θ$
$τ = q \times 2 El sin θ$
$\Rightarrow q = \frac{τ}{2 El s i n θ}$
$\Rightarrow q = \frac{4}{2 \times 2 \times 1 0 ^{5} \times 2 \times 1 0 ^{- 2} \times s i n 3 0 ^{\circ}}$
or $q = 2 m C$

Q. An electric dipole is placed at an angle of 30∘ with an electric field of intensity 2×105NC−1. It experiences a torque equal to 4Nm. Calculate the charge on the dipole if the dipole length is 2cm.

8mC

4mC

8μC

2mC