A parallel plate capacitor whose capacitance C is 14 pF is charged by a battery to a potential difference V = 12V between its plates. The charging battery is now disconnected and a porcelain plate with k = 7 is inserted between the plates, then the plate would oscillate back and forth between the plates with a constant mechanical energy of .......... pJ. (Assume no friction)

Four metallic plates, each with a surface area A, are placed at a distance d from each other as shown in the figure. If points A and B is connected with a battery of emf V, then the charge on the plate a will be   

If q₁ + q₂ = 3q, then the value of the q₁/q₂, for which the force of repulsion between q₁ and q₂ is maximum is

A capacitor of 20 μF is charged to 500 volt and a capacitor 10μF is charged to 200 volt and connected. Then after connecting both of them, the common potential for each will be :–

Three charges Q,(+q) and (+q) are placed at the vertices of an equilateral triangle of side ℓ as shown in the figure. If the net electrostatic energy of the system is zero, then Q is equal to :-

 

A positive charge is moved from low potential point A to a high potential point B. Then the electric potential energy