Electric fields and charges practice · Medium

Assertion: At the centre of the line joining two equal and opposite charges, $E=0$.

Reason: At the centre of the line joining two equal and similar charge, $E \neq 0$.

Point charges $+ 4q, - q$ and $+ 4q$ are kept on the $x$-axis at points $x = 0,x = a$ and $x = 2a$ respectively, then

Surface density of charge on a charged conducting sphere of radius '$R$' in terms of electric intensity '$E$' at a distance '$r$' in free space is $\left(r>R, \varepsilon_0= \text{Permittivity of free space}\right)$

A charge is given velocity perpendicular to uniform electric field then?

Assertion: Initial power delivered by electric field is zero.

Reason: Path of charged particle is circular.

Electric field in a region is $\vec E = 3\hat j\,N/C$. Equipotential surfaces are parallel to

Three electric dipoles of dipole moment ${P}, 2 {P}, 3 {P}$ are placed inside a hollow sphere of radius ' $a$ '. The total electric flux coming out of the sphere is

If a charge on the body is $1 \mathrm{~nC},$ then how many electrons are present on the body?

Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude $18 \times 10^{-22} \mathrm{~Cm}^{-2}$. The electric field between the plates is:

A cube of side $a$ is placed in a uniform electric field ${E}=E_0 \hat{{i}}+E_0 \hat{{j}}+E_0 \hat{{k}}$. Total electric flux passing through the cube would be

The electrostatic field due to a charged
conductor just outside the conductor is:

There are two types of electric charges positive charges and negative charges. The property which differentiates the two types of charges is:

A current in a wire is given by the equation $I = 2{t^2} - 3t + 1$ . The charge through cross section of wire in time interval $t = 3\,s\,\,\,{t_0}t = 5s$ is

An infinite number of electric charges each equal to $5\;nano - coulomb$ (magnitude) are placed along $X$-axis at $x = 1\;cm,\;\;x = 2\;cm,\;\;x = 4\;cm\;\;x = 8\;cm \ldots \ldots \ldots$ and so on. In the setup if the consecutive charges have opposite sign, then the electric field in $Newton/Coulomb$ at $X = 0$ is

$\left[ {\frac{1}{{4\pi {\varepsilon _0}}} = 9 \times {{10}^9}N - {m^2}/{c^2}} \right]$

Two similarly equally charged identical metal spheres $A$ and $B$ repel each other with a force of $2.0 \times 10^{-5} \mathrm{~N}$. $A$ third identical uncharged sphere $C$ is touched to $A$, then placed at the midpoint between $A$ and $B$. Calculate the net electrostatic force on $C$.

Two particles, each having a mass of $5 \mathrm{~g}$ and charge $1.0 \times 10^{-7} \mathrm{C}$, stay in limiting equilibrium on a horizontal table with a separation of $10 \mathrm{~cm}$ between them. The coefficient of friction between each particle and the table is the same. Find the value of this coefficient

Calculate the net charge on a substance consisting of a combination of $7 \times 10^{13}$ protons and $4 \times 10^{13}$ electrons.

Assertion: Force between two point charges at rest is not changed by the presence of third point charge between them.

Reason: Force depends on the magnitude of the first two charges and seperation between them.

Two charges of equal magnitudes and at a distance $r$ exert a force $F$ on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is

A point charge $+\,q$, is placed at a distance d from an isolated conducting plane. The field at a point $P$ on the other side of the plane is

Two bodies are charged by rubbing one against the other. During the process, one becomes positively charged while the other becomes negatively charged. Then

A point charge placed at any point on the axis of an electric dipole at some large distance experiences a force $F$. Find the force acting on the point charge when it's distance from the dipole is doubled.

An electron of mass ${M_e},\;$ initially at rest, moves through a certain distance in a uniform electric field in time ${t_1}.\;$ A proton of mass ${M_p}$ also initially at rest, takes time ${t_2}$ to move through an equal distance in this uniform electric field, neglecting the effect of gravity, the ratio ${t_1}/{t_{2\;}}$ is nearly equal to

An electric charge does not have which of the
following properties?

A charged particle of mass $0.003 \mathrm{~g}$ is held stationary is space by placing it in a downward direction of electric field of $6 \times 10^4 \mathrm{~N} / \mathrm{C}$. Then the magnitude of the charge is

When we touch a pith ball with an electrified plastic rod, some of the negative charges on the rod are transferred to the pith ball and it also gets charged. Thus, pith ball is charged by

In nature, the electric charge of any system is always equal to

A charge of 1 $\mathrm{\mu }$C is divided into two parts such that their charges are in the ratio of 2:3. These two charges are kept at a distance 1 m apart in vacuum. Then, the electric force between them (in N) is

Two conducting spheres have radii $R_1=0.5 \mathrm{~m}$ and $R_2=1 \mathrm{~m}$. Each of them has $300 ~\mu \mathrm{C}$ charge on its surface. If the spheres are joined by a conducting wire then the amount of charge transferred from one body to the other is

Assertion: Two particles of same charge projected with different velocity normal to electric field experience same force.

Reason: A charged particle experiences force, independent of velocity in electric field.

Assertion : When we rub a glass rod with silk, the rod gets negatively charged and the silk gets positively charged.

Reason : On rubbing, electrons from silk cloth move to the glass rod.