Question

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 1

The Correct Option is B

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.