6.In order to increase the capacity of a parallel plate condenser one should introduce between the plates a sheet of

7.A parallel-plate capacitor has two plates of area A and separation d and is charged to a potential difference V. The charging battery is then disconnected and the plates are pulled apart until their separation is 2d. The new potential difference between the plates is

8.If q is the charge on the capacitor and E is the magnitude of the electric field between the plates, the force on each plate of the capacitor is

9.The parallel plates of a capacitor are 1 cm apart. The original potential difference between them is 3000 V, and it decreases to 1000V when a sheet of dielectric of dielectric constant 6 is inserted between the plates. Calculate the thickness of the dielectric sheet.

10.A solid conducting sphere having charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. Let the p.d. between the surface of the solid sphere and that of the outer surface of hollow shell be V. If now shell is given a charge - 3 Q, the new p.d. between the same two surfaces is