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Home » An electric dipole with dipole moment is aligned at with the direction of a uniform electric field of magnitude Calculate the magnitude of the torque acting on the dipole.
An electric dipole with dipole moment 4 \times 10^{-9} C \mathrm{Cm} is aligned at 30^{\circ} with the direction of a uniform electric field of magnitude 5 \times 10^{4} N C^{-1} . Calculate the magnitude of the torque acting on the dipole.
CBSE | Class 12 | Electric Charges and Fields | NCERT | Physics
An electric dipole with dipole moment 4 \times 10^{-9} C \mathrm{Cm} is aligned at 30^{\circ} with the direction of a uniform electric field of magnitude 5 \times 10^{4} N C^{-1} . Calculate the magnitude of the torque acting on the dipole.

Solution:

Given: Electric dipole moment, p=4 \times 10^{-9} C m

Angle made by p with a uniform electric field, \theta=30^{\circ}

Electric field, E=5 \times 10^{4} N C^{-1}

Concept:

Torque acting on the dipole is given by the relation.

\tau=p E \sin \theta

Calculation: We evaluate the value of torque,

\tau=p E \sin \theta =4 \times 10^{-9} \times 5 \times 10^{4} \times \sin 30=20 \times 10^{-5} \times \frac{1}{2}=10^{-4} \mathrm{Nm}

Final Answer: Therefore, the magnitude of the torque acting on the dipole is 10^{-4} \mathrm{Nm}

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