Electric fields and charges practice · Mixed difficulty

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Work done by electric field on moving a positive charge on an equipotential surface is always zero.

Reason (R): Electric lines of forces are always perpendicular to equipotential surfaces.

In the light of the above statements, choose the most appropriate answer from the options given below:

The phenomenon used in the designing of T.V. cables is

When a negative charge is taken at a height from earth’s surface, then its potential energy

A charge $+ q$ is fixed to each of three corners of a square on the empty corner a charge $Q$ is placed such that there is no net electrostatic force acting is no net electrostatic force acting on the diagonally opposite charge. Then

A point charge is kept at the centre of a metallic insulated spherical shell. Then

The electric field intensity just sufficient to balance the earth's gravitational attraction on an electron will be: (given mass and charge of an electron respectively are $9.1 \times 10^{-31} \mathrm{~kg}$ and $1.6 \times 10^{-19} \mathrm{C}$.)

If two bodies are rubbed and one of them acquires $q_1$ charge and another acquires $q_2$ charge, then ratio $q_1 : q_2$ is

Suppose charge on a metallic sphere is $q.$ If the sphere
is put in contact with an identical uncharged sphere,
the charge will spread over the two spheres. By
symmetry charge on each sphere will be ……

When distance between two charged spheres is varied
so that it becomes half the initial distance, force
between them will become ……

The magnitude of electric force experienced by
a charged particle in an electric field depends
on:

Two equal point charges each of $3 \,\mu C$ are separated by a certain distance in metres. If they are located at $(\hat{i}+\hat{j}+\hat{k})$ and $(2 \hat{i}+3 \hat{j}+3 \hat{k}),$ then the electrostatic force between them is

A glass rod rubbed with silk is used to charge a gold leaf electroscope and the leaves are observed to diverge. The electroscope thus charged is exposed to $X$-rays for a short period. Then

There is an electric field $E$ in x-direction. If the work done in moving a change of 0.4 C through distance of 2 m along a line making an angle $60^\circ$ with x-axis is 12 J, then the value of electric field $E$ will be

Assertion (A): In a non-uniform electric field, a dipole will have translatory as well as rotatory motion.
Reason (R): In a non-uniform electric field, a dipole experiences a force as well as torque.

There are two charges $+ 1\;\mu C$ and $+ 5\mathrm{\;}\mu C$ respectively. The ratio of the forces acting on them will be

An electron of mass “M” kg and charge “e” coulomb travels from rest through a potential difference of “V” volt. The final velocity of electron is (in m/s)

Two small spheres each carrying a charge $q$ are placed $r$ metre apart. If one of the sphere is taken around the other one in a circular path of radius $r$, the work done will be equal to

If a point charge $\mathrm{q}$ is placed at the centre of a cube what is the flux linked with the cube?

Assertion: Electric and gravitational fields are acting along same line. When proton and $\alpha$-particle are projected up veritically along that line, the time of flights is less for proton.

Reason: In the given electric field acceleration of a charged particle is directly proportional to specific charge.

Charge on $\alpha$ particle is

$A,B,C$, are three points on a circle of radius $1\,\,cm$. These points from the corners of an equilateral triangle. A charge $2C$ is placed at the centre of the circle. The work done in carrying a charge of $0.1\,\mu C$ from $A$ to $B$ is

Statement-1: A uniformly charged dise has a pin hole at its centre. The electric field at the centre of the disc is zero.
Statement-2: Disc can be supposed to be made up of many rings. Also electric field at the centre of uniformly charged ring is zero.

Plastic rod rubbed with fur and glass rod rubbed with silk

Assertion: Vehicle carrying highly inflammable materials having hanging chains, slightly touching the ground.

Reason: The body of a vechicle gets charged when moving through air at high speed.

The distance between a proton and electron both having a charge $1.6 \times {10^{ - 19}}coulomb,$ , of a hydrogen atom is ${10^{ - 10}}metre.$. The value of intensity of electric field produced on electron due to proton will be

The dimensional formula of electric charge is:

One of the following is not a property of field lines

Two identical conductors of copper and aluminum are placed in an identical electric fields. The magnitude of induced charge in the aluminum will be

Mark the incorrect statement among the following.

Given below are two statements:
Statement I An electric diploe is placed at the centre of a hollow sphere. The flux of electric field through the sphere is zero but the electric field is not zero anywhere in the sphere.
Statement II If $R$ is the radius of a solid metallic sphere and $Q$ be the total charge on it. The electric field at any point on the spherical surface of radius $r( < R)$ is zero but the electric flux passing through this closed spherical surface of radius $r$ is not zero.
In the light of the above statements, choose the correct answer from the options given below.

Two charged particles of same specific charge (i.e. charge per unit mass) are projected in same uniform magnetic field with projection velocities, perpendicular to the magnetic field. If the speeds of charged particles are $v$ and $2 v$, then the ratio of angular speeds of the path of the particles in magnetic field will be