Electric fields and charges practice · Mixed difficulty

Assertion: A point charge is brought in an electric field. The field at a nearby point will increase, whatever be the nature of the charge.

Reason: The electric field is independent of the nature of charge.

Two particles of masses in the ratio $1: 2$, with charges in the ratio $1: 1$, are placed at rest in a uniform electric field. They are released and allowed to move for the same time. The ratio of their kinetic energies will be finally

If the electric flux entering and leaving an enclosed surface respectively are ${\phi _1}$ and ${\phi _2}$, the electric charge inside the surface will be

Assertion: Coulomb force between charges is central force.

Reason: Coulomb force depends on medium between charges.

The electric field in a certain region is given by $\vec{E}=5 \hat{i}-3 \hat{j} k V / m.$ The potential difference $V_B-V_A$ between points $A$ and $B,$ having coordinates $(4,0,3) \,\mathrm{m}$ and $(10,3,0) \,\mathrm{m}$ respectively, is equal to

A circular loop of radius a carries a total charge $Q$ distributed uniformly over its circumference. A small length ${dL}$ of the wire is cut off. The magnitude of electric field at the center due to remaining wire will be $\left[K=\frac{1}{4 \pi \varepsilon_0}\right]$

Assertion: Electrostatic field lines start at positive charges and end at negative charges.
Reason: Field lines are continuous curves without any breaks and they form closed loop.

Electrical force is acting between two charges kept in vacuum. A copper plate is placed between the charges, the force now is

Assertion: Induced charge does not contribute to electric field or potential at a given point.

Reason: A point chagre $q_0$ is kept outside a solid metallic sphere, the elcetric field inside the sphere is Zero.

Statement I: The electrostatic field lines cannot form a closed path

Statement II: The magnetic field lines form a continuous closed path

Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then

When a number of charged liquid drops coalesce, which of the following quantity does not change?

Assertion : Work done in moving a charge between any two points in an electric field is independent of the path followed by the charge, between these points.

Reason: Electrostatic force is a non conservative force.

The Gaussian surface for calculating the electric field due to a charge distribution is

Statement-I: Flux through a closed surface is zero

Statement-II: Total charge inside the surface must be zero

Consider the following two statements
a) Electric field is always conservative in nature.
b) In electromagnetic waves the phase difference between oscillating electric and magnetic field is ${90^\mathrm{o}}$
The corerct statement (s) is/are

An infinite number of charges, each of magnitude $\mathrm{q}$, are placed along $\mathrm{X}$-axis at $\mathrm{x}=1 \mathrm{~m}, 2 \mathrm{~m}, 4 \mathrm{~m}, 8 \mathrm{~m}, 16 \mathrm{~m}$ and so on but the consecutive charges are of opposite sign starting with $+\mathrm{q}$ at $\mathrm{x}=1 \mathrm{~m}$. A point charge $\mathrm{q}_0$, kept at the origin, experiences a force of magnitude:

Two point charges $+ 3\mu C$ and $+ 8\mu C$ repel each other with a force of 40$N$. If a charge of $- 5\mu C$ is added to each of them, then the force between them will become

An electron moves a distance of $6 \mathrm{~cm}$ when accelerated from rest by an electric field of strength $2 \times 10^4 \mathrm{~NC}^{-1}$. Calculate the time of travel. The mass and charge of electron are $9 \times 10^{-31} \mathrm{~kg}$ and $1.6 \times 10^{-19} \mathrm{C}$ respectively.

Electric charge is uniformly distributed along a long straight wire of radius 1mm. The charge per cm length of the wire is ${\cal Q}$ coulomb. Another cylindrical surface of radius 50 cm and length 1m symmetrically encloses the wire. The total electric flux passing through the cylindrical surface is

Calculate the ratio of electric to gravitational force between two electrons.

A negatively charged oil drop is prevented from falling under gravity by applying a vertical electric field $100V\;{m^{ - 1}}.$ If the mass of the drop is $1.6 \times {10^{ - 3}}g,$ the number of electrons carried by the drop is $\left( {g = 10m{s^{ - 2}}} \right)$

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 ….$\times {10^6}\frac{v}{m}$

Statement-1: Total work done by non-uniform electric field on a charged particle starting from rest till any time is non-negative. (assume no other forces act on the charged particle).
Statement-2: The angle between electrostatic force an velocity of the charged particle released from rest in non-uniform electric field is always acute. (assume no other forces act on the charged particle).

If the electrostatic force on a small sphere of charge $0.4 \mu \mathrm{C}$ due to another small sphere of charge $-0.8 \mu \mathrm{C}$ in air is $0.2 \mathrm{~N}.$ The separation of the spheres is $\left(\mathrm{k}=9 \times 10^9 \mathrm{~N} \mathrm{~m}^2 / \mathrm{C}^2\right)$

Assertion: Two charges ${q}_1$ and ${q}_2$ are placed at separation $r$. Then magnitude of force on each charge is $F$.

Reason: Now a third charge ${q}_3$ is placed near ${q}_1$ and ${q}_2$ Then force on ${q}_1$ due to ${q}_2$ remains ${F}$.

The electric field at a distance $\frac{{3R}}{2}$ from the centre of a charged conducting spherical shell of radius $R\;\mathrm{is}\;E$. The electric field at a distance $\frac{R}{2}$ from the centre of the sphere is

Select the correct statements from the following
(i) inside a charged or neutral conductor, electrostatic field is zero
(ii) the electrostatic field at the surface of the charged conductor must be tangential to the surface at any point
(iii) there is no net charge at any point inside the conductor

Two identical conducting balls $A$ and $B$ have positive charges ${q_1}$ and ${q_2}$ respectively but ${q_1} \ne {q_2}.$ The balls are brought together so that they touch each other and then kept in their original positions. The force between them is

A $10\,\mu C$ charge is divided into two equal parts and kept at 1 cm distance. Find repulsion between charges.