Electric fields and charges practice · Medium

A proton and an electron are placed in a uniform electric field then

Two spherical conductors A and B of radii 1mm and 2mm are separated by a distance of 5cm and are uniformly charged. If the spheres are connected by a conducting wire then in equilibrium condition, the ratio of the magnitude of the electric fields at the surfaces of spheres A and B is

The electric field in a region of space is given by $\overrightarrow E = 5\widehat i + 2\widehat j\,\,N{C^{ - 1}}$. The electric flux due to this field through an area $2{m^2}$ lying in the YZ plane in S.I. Units is

Assertion:- Electric field lines are always perpendicular to the surface of conductor.
Reason:-Electric field is always perpendicular to equipotential surface.

If point charges $Q_1=2 \times 10^{-7} \mathrm{C}$ and $Q_2=3 \times 10^{-7} \mathrm{C}$ are at $30 \mathrm{~cm}$ separation, then find electrostatic force between them

A positive charge of $17.7 \mu \mathrm{C}$ is placed at the centre of a hollow sphere of radius $0.5 \mathrm{~m}$. Calculate the flux density through the surface of the sphere.

The electric field inside a spherical shell of uniform surface charge density is

Two spheres of copper of the same radii, one hollow and other solid, are charged to the same potential. The hollow sphere has

The force between two point charges placed in a material medium of dielectric constant $\varepsilon_\text{r}$ is $\text{F}.$ If the material is removed, then the force between them becomes

A conducting sphere of radius $R$, carrying charge $Q$, lies inside an uncharged conducting shell of radius $2R$. If they are joined by a metal wire,

(A) $Q/3$ amount of charge will flow from the sphere to the shell

(B) $2Q/3$ amount of charge will flow from the sphere to the shell

(C) $Q$ amount of charge will flow from the sphere to the shell

(D) amount of heat will be produced $K Q^2 / 4 R$

Top of the stratosphere has an electric field $E$ (in units of $V/m$) nearly equal to

The intensity of electric field at the surface of conducting hollow sphere is $10\, \mathrm{NC}^{-1}$ and its radius is $10 \mathrm{~cm}$. The value of electric field at the centre of sphere is

Two identical conducting spheres carrying different charges attract each other with a force $F$ when placed in air medium at a distance $d$ apart. The spheres are brought into contact and then taken to their original positions. Now the two spheres repel each other with a force whose magnitude is equal to that of the initial attractive force. The ratio between initial charges on the spheres is

Electric charge between two bodies can be produced by

Consider $\overrightarrow {{E_1}} = x\hat i + \hat j$ and $\overrightarrow {{E_2}} = x{y^2}\hat i + {x^2}y\;\hat j;$ then

Select the correct statements. Coulomb's law correctly describes the electric force that:
(i) binds the electrons of an atom to its nucleus.
(ii) binds the protons and neutrons in the nucleus of an atom.
(iii) binds atoms together to form molecules.

A Gaussian sphere encloses an electric dipole within it. The total flux across the sphere is

A simple pendulum of period $T$ has a metal bob which is negatively charged. If it is allowed to oscillate above a positively charged metal plate, its period will

A proton and an electron are released from
an infinite distance apart and they get
attracted towards each other. Which of the
following statement about their kinetic
energy is true?

Electrical force between two point charges is 200N. If we increase 10% charge on one of the charges and decrease 10% charge on the other, then electrical force between them for the same distance becomes __________ N

Two insulated charged metallic spheres $P$ and $Q$ have their centres separated by a distance of $50 \mathrm{~cm}$. The radii of $P$ and $Q$ are negligible compared to the distance of separation. The mutual force of electrostatic repulsion if the charge on each is $3.2 \times 10^{-7} \mathrm{C}$ is:

A comb run through one’s dry hair attracts small bits of paper. This is due to

$F_g$ and $F_e$ represents gravitational and electrostatic force respectively between electron and proton at a distance of $10 \mathrm{~cm}$. The ratio of $F_g / F_e$ is of the order of

A positively charged thin metal ring of radius
$R$ is fixed in the xy-plane, with its centre at the
origin. A negatively charged particle is released
from rest at the point $P (0, 0, c)$ where $c > 0.$

Consider the following statements:
(A) The electric field at $P$ due to the metallic ring
is always directed towards origin.

(B) The negatively charged particle is accelerated
towards origin and undergoes periodic
motion.

Which of the above statements is/are correct?

Additive nature of charge means

A capacitor of capacitance $C$ is charged to potential $V.$ The flux of the electric field through a closed surface enclosing the capacitor is

A solid sphere of radius $R$ has a charge ${\cal Q}$ distributed in its volume with a charge density $\mathrm{\rho } = k{r^a},$ where $k\;\;\mathrm{and\;}a\mathrm{\;}$ are constants and $r$ is the distance from its centre. If the electric field at $r = \frac{R}{2}$ is $\frac{1}{8}$ times that at $r = R,$ find the value of $a.$

A tin nucleus (atomic number Z = 50) has a radius of $6.6 \times {10^{ - 15}}\,m$. The potential on its surface will be (the charge on the proton $= 1.6 \times {10^{ - 19}}\,C$)

A thin metallic spherical shell contains a charge $Q$ on its surface. A point charge $\mathrm{q}_1$ is placed at the centre of the shell and another charge $\mathrm{q}_2$ is placed outside the shell. All the three charges are positive. Then the force on charge $\mathrm{q}_1$ is -

When a body is earth connected, electrons from the earth flow into the body. This means the body is