Electric fields and charges practice · Medium

A cube of metal is given a positive charge $Q.$ For the above system, which of the following statements is true

Force of attraction between two point charges $Q$ and $-Q$ separated by $d\;meter$ is ${F_e}$. When these charges are placed on two identical spheres of radius $R = 0.3d$ whose centres and $d\;meter$ apart, the force of attraction between them is

An electron of mass $m$ and charge $e$ is accelerated from rest through a potential difference $V$ in vacuum. The final speed of the electron will be

Charge on $\alpha$ particle 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

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

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

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.

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

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

A polythene piece, rubbed with wool, is found to have negative charge of $4 \times {10^{ - 7}}$C. the number of electrons transferred from wool to polythene is

Flux coming out from a unit positive charge enclosed in air is

A charged particle of mass $5 \times {10^{ - 5}}kg$ is held stationary in space by placing it in an electric field of strength ${10^7}N{C^{ - 1}}$ directed vertically downwards. The charge on the particle is

According to Gauss’ Theorem, electric field of an infinitely long straight wire is proportional to

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

A current carrying wire in the neighborhood produces

A force $F$ acts between sodium and chlorine ions of salt (sodium chloride) when put 1cm apart in air. The permittivity of air and dielectric constant of water are ${\varepsilon _0}$ and $K$ respectively. When a piece of salt is put in water electrical force acting between sodium and chlorine ions $1cm$ apart is

The law, governing the force between electric charge is known as