A point charge $$q$$ is placed at the corner of a cube of side $$a$$ as shown in the figure. What is the electric flux through the face $$A B C D$$ ?
The electric field lines on the left have twice the separation on those on the right as shown in figure. If the magnitude of the field at $$A$$ is $$40 \mathrm{~Vm}^{-1}$$, what is the force on $$20 \mu \mathrm{C}$$ charge kept at $$B$$ ?
An infinitely long thin straight wire has uniform charge density of $$\frac{1}{4} \times 10^{-2} \mathrm{~cm}^{-1}$$. What is the magnitude of electric field at a distance $$20 \mathrm{~cm}$$ from the axis of the wire?
A dipole moment $$p$$ and moment of inertia $$I$$ is placed in a uniform electric field $$\mathbf{E}$$. If it is displaced slightly from its stable equilibrium position, the period of oscillation of dipole is