Question
Physics Question on Electrostatic potential
An electric dipole with dipole moment 4 x 10-9 Cm is aligned at 30 degree with the direction of the uniform electric field of magnitude 5 x 104 NC-1. The magnitude of the torque acting on the diapole is
A
10-5 Nm
B
10-4 Nm
C
10 x 10-3 Nm
D
√ 3 x 10-4 Nm
Answer
10-4 Nm
Explanation
Solution
The torque acting on an electric dipole in a uniform electric field is given by the formula:
τ = pE sin θ
Given:
p = 4 x 10-9 Cm
E = 5 x 104 NC-1
θ = 30 degrees
Substituting the values into the formula:
τ = (4 x 10-9 Cm)(5 x 104 NC-1) sin(30°)
Using the value of sin(30°) = 1/2:
τ = (4 x 10-9 Cm)(5 x 104 NC-1) (1/2)
= (20 x 10-5 Cm)(1/2)
= 10 x 10-5 Cm
= 10-4 Nm
Therefore, the magnitude of the torque acting on the dipole is 10-4 Nm. The correct answer is (B) 10-4 Nm.