Electrostatics Part 3

Two small spherical balls of mass 10 g each with charges −2µC and 2µC, are attached to two ends of very light rigid rod of length 20 cm . The arrangement is now placed near an infinite nonconducting charge sheet with uniform charge density of 100µC∕m2 such that length of rod makes an angle of 30∘ with electric field generated by charge sheet. Net torque acting on the rod is:
(Take ε0=8.85×10−12C2∕Nm2 )