Electric fields and charges practice · Mixed difficulty

An electron is liberated from the lower of the two large parallel metal plates separated by a distance of $20 \mathrm{~mm}$. The upper plate has a potential of $+2400 \mathrm{~V}$ relative to the lower plate. How long does the electron take to reach the upper plate? Take $\frac{e}{m}$ of electrons $1.8 \times 10^{11} \mathrm{~C} \mathrm{~kg}^{-1}$.

Two charges of $50\,\mu c$ and $100\,\mu c$ are separated by a distance of $0.6\,m$. The intensity of electric field of a point midway between them is ….$\times {10^6}\frac{v}{m}$

The work done in placing a charge of $8 \times 10^{-18}$ coulomb on a condenser of capacity 100 micro-farad is

A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from the centre is directed

A spherical rubber balloon carries a charge, uniformly distributed over the surface. As the balloon is blown up and increases in size, the total electric flux coming out of the surface

Two conducting spheres of radii ${R_1}$ and ${R_2}$ having charges ${Q_1}$ and ${Q_2}$ respectively are connected to each other. There is

The force between two charged particle placed in air at separation $x$ is $F_0$. Both the charged particle immerged in a medium of dielectric constant $K$ without changing separation between two charge, then net force on one of the particle is now

Given below are two statements:
Statement I: The electric force changes the speed of the charged particle and hence changes its kinetic energy; whereas the magnetic force does not change the kinetic energy of the charged particle.
Statement II: The electric force accelerates the positively charged particle perpendicular to the direction of electric field. The magnetic force accelerates the moving charged particle along the direction of magnetic field.
In the light of the above statements, choose the most appropriate answer from the options given below:

One metallic sphere $A$ is given positive charge whereas another identical sphere $B$ of exactly same mass as of $A$ is given equal amount of negative charge. Then

The net electric flux associated with a closed surface which encloses $1 \mathrm{C}$ positive charge is equal to (In SI unit)

The point charges $Q$ and $- 2Q$ are placed at same distance apart. If the electric field at the location of $Q$ is $E$, find its value at the location of $- 2Q$ is

For coulomb force to be operative the least side of atom will be

At a point in space, the electric field points towards north. In the region surrounding this point, the rate of change of potential will be zero along

A force of 16 N is acting between two charges in air. If the space between them is completely filled with glass $\left( {{ \in _r} = 10} \right),$ then new force will be

The Electric field at a point is

The total electric flux through a cube when a charge $8q$ is placed at one corner of the cube is

In Van de Graaff generator, the process of spraying the charge is called:

Select the correct statements from the following:

I. The electric field due to a charge outside the Gaussian surface contributes zero net flux through the surface.

II. Total flux linked with a closed body, enclosing any charges will be zero.

III. Total electric flux, if a dipole is enclosed by a surface is zero.

Consider the following statements and select the incorrect statement.

An electric dipole is put in north-south direction in a sphere filled with water. Which statement is correct

Electric field intensity at a point outside uniformly charged thin infinite plane sheet is '$\text{E}_1$'. The electric field intensity at a point near and outside the surface of a positively charged conductor of any shape is '$\mathrm{E}_2$'. The relation between magnitude of $\text{E}_1$ and $\text{E}_2$ is (assumed air as the medium)

The electric flux through a closed surface area $S$ enclosing charge ${\cal Q}$ is $\phi$. If the surface area is doubled, then the flux is

When a glass rod is rubbed with a silk cloth, charge
appears on both. This observation is consistent with
law of conservation of charge as

In general, metallic ropes are suspended from the
carriers to the ground which take inflammable material.
The reason is

The number of electric lines of force emerging from $1C$ of positive charge in vaccum is ______ $\times \,{10^{11}}$

A cubical Gaussian surface encloses 24 C of charge. The electric flux through each surface of the cube is

Consider a conductor with a spherical cavity in it. A point charge $q_0$ is placed at the centre of cavity and a point charge $Q$ is placed outside conductor.

Statement-1: Total charge induced on cavity wall is equal and opposite to the charge inside.

Statement-2: If cavity is surrounded by a Gaussian surface, where all parts of Gaussian surface are located inside the conductor, $\int E.d A=0;$ hence $q_{\text {induced}}=-q_0$

Assertion: An electrostatic field line never form closed loop

Reason: Electrostatic field is a conservative field

64 drops each having the capacity $C$ and potential $V$ are combined to form a big drop. If the charge on the small drop is $q,$ then the charge on the big drop will be

When a positively charged body is earthed electrons from the earth flow into the body. This means the body is