Electric fields and charges practice · Medium

An electric dipole is put in north-south direction in a sphere filled with water. Which statement is correct

Electric field intensity at a point outside uniformly charged thin infinite plane sheet is '$\text{E}_1$'. The electric field intensity at a point near and outside the surface of a positively charged conductor of any shape is '$\mathrm{E}_2$'. The relation between magnitude of $\text{E}_1$ and $\text{E}_2$ is (assumed air as the medium)

The electric flux through a closed surface area $S$ enclosing charge ${\cal Q}$ is $\phi$. If the surface area is doubled, then the flux is

When a glass rod is rubbed with a silk cloth, charge
appears on both. This observation is consistent with
law of conservation of charge as

In general, metallic ropes are suspended from the
carriers to the ground which take inflammable material.
The reason is

The number of electric lines of force emerging from $1C$ of positive charge in vaccum is ______ $\times \,{10^{11}}$

A cubical Gaussian surface encloses 24 C of charge. The electric flux through each surface of the cube is

Consider a conductor with a spherical cavity in it. A point charge $q_0$ is placed at the centre of cavity and a point charge $Q$ is placed outside conductor.

Statement-1: Total charge induced on cavity wall is equal and opposite to the charge inside.

Statement-2: If cavity is surrounded by a Gaussian surface, where all parts of Gaussian surface are located inside the conductor, $\int E.d A=0;$ hence $q_{\text {induced}}=-q_0$

Assertion: An electrostatic field line never form closed loop

Reason: Electrostatic field is a conservative field

64 drops each having the capacity $C$ and potential $V$ are combined to form a big drop. If the charge on the small drop is $q,$ then the charge on the big drop will be

When a positively charged body is earthed electrons from the earth flow into the body. This means the body is

Four metal conductors having different shapes
 I. A sphere 
 II. Cylinder
 III. Pear
 IV. Lightning conductor
 are mounted on insulating stands and charged. The one which is best suited to retain the charges for a longer time is

The electric field at a distance $2 \mathrm{~cm}$ from the centre of a hollow spherical conducting shell of radius $4 \mathrm{~cm}$ having a charge of $2 \times 10^{-3} \mathrm{Con}$ its surface is

A body is negatively charged means

Which of the following statements is/are correct?
I. For practical purposes, the earth is used as a reference at zero potential in electrical circuits.
II. The electrical potential of a sphere of radius $R$ with charge $Q$ uniformly distributed on the surface is given by $\frac{Q}{4 \pi \varepsilon_0 R}$.
III. Work done in carrying a point charge from one point to another in an electrostatic field depends on the path along which the point charge is carried.

A positively charged insulator is brought near (but does not touch) two metallic sphere that are in contact. The metallic spheres are then separated. The sphere which was initially farthest from the insulator will have:

A charge $\text{q}$ is fixed. Another charge $\text{Q}$ is brought near it and rotated in a circle of radius $\text{r}$ around it. Work done during rotation is

Regarding a semiconductor which one of the following statements is wrong?

Suppose a rod is given a negative charge by
rubbing it with wool. Which one of the
following statements is correct in this case?

A surface $S=10 \hat{{j}}$ is kept in an electric field ${E}=2 \hat{{i}}+4 \hat{{j}}+7 \hat{{k}}$. How much electric flux will come out through this surface?

A particle of mass $m$ and charge $q$ is placed at rest in a uniform electric field $E$ and then released. The kinetic energy attained by the particle after moving a distance $y$ is

Assertion: The potential difference between any two points in an electric field depends only on initial and final position.

Reason: Electric field is a conservative field so the work done per unit positive charge does not depend on path followed.

An electric dipole placed in a non-uniform electric field experiences

Assertion: The property that the force with which two charges attract or repel each other are not affected by the presence of a third charge.

Reason: Force on any charge due to a number of other charge is the vector sum of all the forces on that charge due to other charges, taken one at a time.

Assertion: Coulomb force and gravitational force follow the same inverse-square law.
Reason: Both laws are same in all aspects.

In charging by induction,

The force of repulsion between two electrons at a certain distance is $2 F$. The force between two protons separated by the same distance is: $\left(m_p=1836\right.\left.{m}_e\right)$

Electric field line at the surface of equipotential surface is

If a charged particle $(+q, m)$ is projected along $+x$ direction with initial velocity $u$ and an uniform electric field exist in space along ($-$ve) $y$-direction then path of partcile is (neglect gravity)

Choose the incorrect statement.