Electric fields and charges practice · Mixed difficulty

Charge on $\alpha$ particle is

If volume change density inside a solid sphere of radius ${R}$ varies with distance $r$ from centre of sphere as $\rho=\rho_0 \frac{r}{R} ; \rho_0=$ constant then find electric field intensity at distance ${r}(<{R})$ from centre is

Two small conducting spheres of equal radius have charges $+ 10\mu C$ and $- 20\mu C$ respectively and placed at a distance $R$ from each other experience force ${F_1}$. If they are brought in contact and separated to the same distance, they experience force ${F_2}$. The ratio of ${F_1}$ to ${F_2}$ is

Two conducting sphere of radii $r_1$ and $r_2$ are charged to the same surface charge density. The ratio of electric field near their surface is

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

Two charges $q$ and $3 q$ are separated by a distance ' $r$ ' in air. At a distance $x$ from charge $q$, the resultant electric field is zero. The value of $x$ is :

The scientist whose major contribution is
towards the measurement of electronic charge

A sphere of radius 1 m encloses a charge of $5\mu C.$ Another charge of $-5 \mu C$ is placed inside the sphere.
The net electric flux would be

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

Assertion (A): Net dipole moment of a polar
linear isotropic dielectric substance is not zero
even in the absence of an external electric field.

Reason (R): In absence of an external electric
field, the different permanent dipoles of a polar
dielectric substance are oriented in random
directions.

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

Electric lines of forces are

A force of 2.25 N acts on a charge of $15 \times {10^{ - 4}}$. Calculate the intensity of electric field at that point

A uniformly charged disc of radius $R$ having surface charge density $\sigma$ is placed in the xy- plane with its centre at the origin. Find the electric field intensity along the $z$ –axis at a distance $Z$ from origin

When a dielectric material is introduced between the plates of a charged condenser then electric field between the plates

A body has a charge of $9.6 \times {10^{ - 20}}$ coulomb. It is

Two point charges repel each other with a force of 100 N. One of the charges is increased by 10% and other is reduced by 10%. The new force of repulsion at the same distance would be

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.

Two uniformly charged spherical conductors $A$ and $B$ of radii $5 \mathrm{~mm}$ and $10 \mathrm{~mm}$ are separated by a distance of $2 \mathrm{~cm}$. If the spheres are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitude of the electric fields at the surface of the sphere $A$ and $B$ will be

The surface charge density $\left( {\mathrm{in\;}C/{m^2}} \right)$ of the earth is about

Infinite charges of magnitude q each are lying at $x = 1,2,4,8..$ metre on X-axis. The value of intensity of electric field at point $x = 0$ due to these charges will be

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

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.

If two point charges 5 C and 10 C are separated by a distance of 10 cm in air. What is electrostatic force between them is

Assertion:- For a charged shell, potential inside shell depends only on the field inside shell.
Reason:- Potential of shell may be determined only by the field outside.

The ratio of the forces between two small spheres with constant charge $\left( a \right)$ in air $\left( b \right)$ in a medium of dielectric constant $K$ is

The dimensional formula of electric charge is:

Identify the wrong statement in the following. Coulomb’s law correctly described the electric force that

A charged particle of mass m and charge q is released from rest in a uniform electric field E. The KE of particle after time t is:

Electric charge between two bodies can be produced by

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

A conducting sphere of radius $10cm$ is charged $10\mu \;C.$ Another uncharged sphere of radius $20\;cm$ is allowed to touch it for some time. After that if the sphere are separated, then surface density of charges, on the spheres will be in the ratio of