List of top Physics Questions on Electric charges and fields

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 long charged cylinder of linear charge density \(\lambda\) is surrounded by a hollow coaxial conducting cylinder. The magnitude of electric field in the space between the two cylinders at a distance \(R\) from the common axis of the cylinders is
A simple pendulum has a bob of mass m carrying a positive charge q. It is placed in a region where a uniform electric field E is directed vertically upwards. If the string is displaced slightly and released, what happens to its time period T compared to its time period T$_0$ without the electric field?
A charge Q is placed at the center of an uncharged, hollow, conducting spherical shell. What is the electric field at a point outside the shell at a distance r from the center, and what is the net charge on the outer surface of the shell?
Two identical conducting spheres, one carrying a charge of +4q and the other carrying -2q, are kept at a distance r apart in a vacuum. The magnitude of the electrostatic force between them is F. If they are brought into contact and then separated to the same distance r, what is the new electrostatic force between them?

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?
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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 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:
At a distance of 20 cm from the centre of a charged conducting sphere of radius 10 cm, the electric field due to the sphere is $9000NC^{-1}$ If an electric charge of 3 µC is placed at a distance of 30 cm from the centre of the sphere, then the electrostatic force acting on the charge is}
In an isosceles right angled triangle ABC, the equal sides AB and AC are 10 cm. Charges \(+5\mu C\), \(+20\mu C\) and \(+20\mu C\) are placed at A, B and C respectively. A charge \(+2\mu C\) is placed at the midpoint of BC. The net electrostatic force on it is:
If $\phi_A$ and $\phi_B$ are the electric fluxes leaving and entering a Gaussian surface respectively, then the charge enclosed is:
If three electric charges each of magnitude 20 µC are placed at any three corners of a square of side $\sqrt{2}\,m$, then the net electric field at the centre of the square (in $10^{5}NC^{-1}$) is}
An electron is moving in a stable circular orbit of radius $0.1\text{ m}$ around a thin infinitely long positively charged straight wire. If the orbital velocity of the electron around the wire is $4 \times 10^7\text{ ms}^{-1}$, then the linear charge density of the wire is nearly:
A pith ball of mass $m$ grams and charge $Q$ is suspended using a massless silk thread near a large charged conducting metal sheet of area $A$ and surface charge density $\sigma$. If the silk thread makes an angle $\theta$ with the metal sheet, then $\tan\theta$ is equal to:
Two point charges $P = +25\mu\text{C}$ and $Q = -16\mu\text{C}$ are placed $5\text{ cm}$ apart. Find the position of the point at which the resultant electric field is zero: