List of top Physics Questions on Electric charges and fields asked in UP Board XII

Option 1: Write down the definition of electric dipole moment. Derive the formula for the electric field intensity at an axial point of an electric dipole.
OR
Option 2: In the given combination of capacitors (connected across a 22 V supply), find out (i) the total capacitance, (ii) the charge on the 4 \( \mu\text{F} \) capacitor and (iii) the total stored energy. The network contains capacitors of 4 \( \mu\text{F} \), 2 \( \mu\text{F} \), 1 \( \mu\text{F} \), 2 \( \mu\text{F} \), 1 \( \mu\text{F} \) and 12 \( \mu\text{F} \).

State Gauss' law in electrostatics. Charge inside a Gaussian surface is zero. Comment on the electric field intensity at each point of the surface.

Electric field lines do not intersect. Why?

In the followings, dimension of electric field is:

Find out the formula for the electric field at a point outside a uniformly charged spherical shell by using Gauss's theorem.

Coulomb's repulsive force of \( F \) newton acts between two point charges of \( +3\,\mu C \) and \( +8\,\mu C \). If \( -5\,\mu C \) charge is given to both of them, then the force and its nature between them will be:

Option 1: What is Gauss's law? The figure shows a cylinder placed in an electric field \(\vec{E}=100\,\hat{i}\ \text{N/C}\). \(\vec{E}\) is positive when \(x>0\) and negative when \(x<0\). Length of the cylinder is \(30\ \text{cm}\) and radius of each plane surface is \(3.5\ \text{cm}\); its centre is at O. Find the electric fluxes \(\phi_1,\ \phi_2\) and \(\phi_3\) linked with each plane and the curved surface respectively. What will be the net charge inside the cylinder?
OR
Option 2: Obtain the formula for the capacitance of a parallel plate capacitor when a dielectric medium is partially filled in between its plates.

A proton, an electron and an \(\alpha\)-particle placed in a uniform electric field experience forces \(F_1\), \(F_2\) and \(F_3\) respectively. Then:

A force of 80 newton acts between two point charges placed in air at a fixed distance. When the same charges are placed at the same distance in a dielectric medium, the force becomes 8 newton. The dielectric constant of the medium is:

Two point charges \( +10\,\mu C \) and \( -10\,\mu C \) are situated 2 cm apart. This dipole is placed in a uniform electric field of \( 1\times10^{5} \) volt/metre. Calculate the energy required to rotate the dipole from the position of \( 0^\circ \) to \( 180^\circ \).

The number of electrons that must be removed from a piece of metal to give it a charge of \( 1\times10^{-7} \) coulomb will be:

A non-conducting cylinder is placed inside the electric field (E). The axis of the cylinder is parallel to the electric field. How much will be the total electric flux passing through the cylinder?

If electric field lines are mutually intersecting, then what is the meaning indicated?

Two electrons in air are at a distance of 1 m. Gravitational and electrostatic forces acting between them are \( F_1 \) and \( F_2 \) respectively. If the dielectric constant of the medium between them becomes infinite, then: