Q.

An electric dipole is placed at an angle of 30° with an electric field of intensity 2×105N C-1. It experiences a torque equal to 4 Nm. Calculate the magnitude of charge on the dipole, if the dipole length is 2 cm.        [2023]
 

1 4 mC  
2 2 mC  
3 8 mC  
4 6 mC  

Ans.

(2)

Given, angle, θ=30°,

Electric field intensity, E=2×105 N C-1

τ=4 Nm, Dipole length, l=2 cm=0.02 m

τ=pEsinθ=(ql)Esinθ

    q=τElsinθ=42×105×0.02×12=2 mC