A positive charge Q is situated at the centre of a cube. The electric flux through any face of the cube is (in SI units)

A charge of 0.8 coulomb is divided into two charges Q₁ and Q₂. These are kept at a separation of 30 cm. The force on Q₁ is maximum when

A particle with charge Q coulomb, tied at the end of an inextensible string of length R metre, revolves in a vertical plane. At the centre of the circular trajectory, there is a fixed charge of magnitude Q coulomb. The mass of the moving charge M is such that $$Mg = {{{Q^2}} \over {4\pi {\varepsilon _0}{R^2}}}$$. If at the highest position of the particle, the tension of the string just vanishes, the horizontal velocity at the lowest point has to be

A unit negative charge with mass M resides at the mid-point of the straight line of length 2a adjoining two fixed charges of magnitude +Q each. If it is given a very small displacement x(x << a) in a direction perpendicular to the straight line, it will