An electric dipole is placed at an angle of 30 ° with an electric...

Torque on the dipole in uniform electric field is given as $τ = PEsin \theta$

$⇒ τ = qlEsin \theta$

$⇒ q = \dfrac{τ}{lEsin \theta}$$= \dfrac{4}{2 \times {10}^{- 2} \times 0.5 \times 2 \times {10}^{5}} = 2 \times {10}^{- 3}C$

Hence, charge on dipole is $2mC$.