Class-12th Physics, CBSE and UP Board
Electric Charges and Fields,
Chapter-1, Exercise -1, Q-1.10
NCERT Solutions for Class 12th Physics
An electric dipole with dipole moment 4 × 10⁻⁹ C m is aligned at 30° with the direction of a uniform electric field of magnitude 5 × 10⁴ NC⁻¹. Calculate the magnitude of the torque acting on the dipole.
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Electric dipole moment, p = 4 x 10-9 C m
Angle made by p with a uniform electric field, Θ= 30°
Electric field, E = 5 x 104 N C⁻1
Torque acting on the dipole is given by the relation,
τ = pE sinΘ = 4 x 10⁻9 x 5 x 104 x sin 30 = 20 x 10⁻5 x 1/2= 10⁻4 Nm Therefore, the magnitude of the torque acting on the dipole is 10⁻4 N m.