Question

A charge + Q is placed on a thin conducting spherical shell of radius R. Use Gauss's theorem to derive an expression for the electric field at a point lying (i) inside and (ii) outside the shell.

Show that the electric field for same charge density (σ) is twice in case of a conducting plate or surface than in a nonconducting sheet.

A parallel-plate capacitor is charged by a battery to a charge Q, and the battery is then disconnected. A dielectric slab of dielectric constant K is now fully introduced between the plates. The changes in capacitance C, charge Q and potential difference V are respectively:

Read the following statements about a parallel-plate capacitor and identify the correct option: (I) The capacitance of a parallel-plate capacitor in vacuum is given by C = ε0A/d, where A is the area of each plate and d is the separation between them. (II) When a dielectric slab of dielectric constant K is fully inserted between the plates, the capacitance becomes K times its earlier value. (III) The energy stored per unit volume (energy density) in the electric field between the plates (in vacuum) is u = ½ ε0E². (IV) If the plates of an isolated charged capacitor are pulled farther apart at constant charge, the energy stored in the capacitor decreases.