Question

An electric dipole when held at 30 degree with respect to uniform electric field of 10 of power 4 N/C expsriences a torque of 9×10 of power 26 N/C. Calculate the dipole moment ?

Answer 1

Electric dipole moment, p = 4 × 10−9 C m (Given)

Angle made by p with a uniform electric field, θ = 30° (Given)

Electric field, E = 5 × 104 N C−1 (Given)

Torque acting on the dipole is given by the relation,

τ = pE sinθ

= 4 × 10-9 × 5 × 104 × sin 30

= 20 × 10-5 × 1 half

= 10-4 Nm

Therefore, the magnitude of the torque acting on the dipole is 10−4 N m.

Answer 2

Note: The correct question is-

An electric dipole when held at $30^{\circ}$ with respect to uniform electric field of  $10^{4} N/C$ experiences a torque of $9\times 10^{-26} Nm$.

Calculate the dipole moment of the dipole ?

Step 1: Given data

Electric field, $E=10^{4} N/C$

Torque, $\tau=9\times 10^{-26} Nm$

Angle, $\theta=30^{\circ}$

dipole moment, $p=?$

Step 2: Calculating the dipole moment

We know that,

$\tau= pEsin\theta$

Thus, dipole moment is calculated as,

$p=\frac{\tau}{Esin\theta} =\frac{9\times 10^{-26} }{10^{4} \times sin30^{\circ}}$

$p=\frac{9\times 10^{-26} }{10^{4} \times 0.5}=1.8\times 10^{-19}Cm$

Hence, the dipole moment of the dipole is $1.8\times 10^{-19}Cm$.

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