The formula to calculate the dipole moment is given by
∣p⇀∣=q∣d⇀∣...(1)
Substitute the values of the known parameters into equation (1) to calculate the dipole moment.
∣p⇀∣==0.01C×0.4mm×103mm1m4.0×10−6C⋅m
The formula to calculate the torque on the dipole in the electric field is given by
∣τ∣=∣p×E∣...(2)
Substitute the values of the known parameters into equation (2) to calculate the required torque.
∣τ⇀∣==4.0×10−6C⋅m×10dyne⋅C−1×105dyne1N×sin30∘2×10−10Nm