CBSE Class 12 Physics — Electrostatic Potential and Capacitance

In a region, the electric potential varies as $V = 10 - 50x$, where V is in volts and x in meters. The electric field in the region is:

A conducting wire connects two charged metallic spheres A and B of radii $r_1$ and $r_2$ respectively. The distance between the spheres is very large compared to their radii. The ratio of electric fields, ($E_A/E_B$) at the surfaces of spheres A and B will be

A parallel plate capacitor of capacitance C has a dielectric slab between its plates. It is charged to a potential difference V by connecting it across a battery. The battery is then disconnected. If the dielectric slab is now withdrawn from the capacitor, how will the following be affected? (a) Capacitance of the capacitor, (b) Energy stored in the capacitor, and (c) The potential difference between the plates of the capacitor. Justify your answer in each case.