Vardaan Learning Institute

The SI unit of electric charge is ____________.

The magnitude of elementary charge on a proton is exactly ____________ C.

When a glass rod is rubbed with silk, the glass rod acquires a ____________ charge.

Which of the following is the true test of electrification?
(A) Attraction     (B) Repulsion     (C) Both     (D) None

The number of electrons present in $1\text{ C}$ of charge is approximately:
(A) $6.25 \times 10^{18}$     (B) $1.6 \times 10^{-19}$     (C) $6.25 \times 10^{19}$     (D) $1.6 \times 10^{19}$

The law of conservation of charge states that:
(A) Charge cannot be created or destroyed isolatedly.
(B) The total charge of an isolated system remains constant.
(C) Charges can be created in equal and opposite pairs.
(D) All of the above are correct interpretations.

Define the quantization of charge and state its formula.

What does the equation $q_1 + q_2 = 0$ signify in electrostatics?

Can a physical body have a total charge of $4.8 \times 10^{-19}\text{ C}$? Give a reason.

Distinguish basically between conductors and insulators.

What is meant by the process of "grounding" or "earthing"?

What is charging by induction?

Match the following concepts correctly:

(a) Positive charge on a body	(i) Given by $q = ne$
(b) Negative charge on a body	(ii) Arises due to excess of electrons
(c) Quantization principle	(iii) Arises due to deficiency of electrons

The numerical value of $1/(4\pi\epsilon_0)$ in vacuum is ____________ $\text{Nm}^2/\text{C}^2$.

The constant $\epsilon_0$ is known as the ____________ of free space.

The electrostatic force between two point charges separated by distance $r$ is proportional to:
(A) $r$     (B) $r^2$     (C) $1/r$     (D) $1/r^2$

If a dielectric medium of constant $K$ is introduced between two point charges, the force between them:
(A) increases $K$ times     (B) decreases $K$ times     (C) remains the same     (D) becomes zero

Relative permittivity (Dielectric constant) $\epsilon_r$ is defined as the ratio:
(A) $\epsilon_0 / \epsilon$     (B) $\epsilon / \epsilon_0$     (C) $\epsilon_0 \times \epsilon$     (D) $\epsilon_0 + \epsilon$

State Coulomb's law in electrostatics.

Write Coulomb's law strictly in vector form.

What is the accepted dielectric constant ($K$) for a perfectly conducting metal?

State the principle of superposition for electrostatic forces.

Two point charges $+1\mu\text{C}$ and $+5\mu\text{C}$ are placed at a distance. What is the ratio of the forces acting on them?

Match the physical quantities to their standard SI values:

(a) $1/(4\pi\epsilon_0)$	(i) Vector sum of individual forces
(b) $\epsilon_0$	(ii) $9 \times 10^9 \text{ Nm}^2/\text{C}^2$
(c) Superposition principle	(iii) $8.854 \times 10^{-12} \text{ C}^2/\text{Nm}^2$

The SI unit of electric field intensity is ____________ or $\text{V/m}$.

The electric field inside a hollow conducting charged sphere is perfectly ____________.

Electric field lines always diverge away from a ____________ charge.

The magnitude of the electric field due to a point charge varies with distance $r$ as:
(A) $1/r$     (B) $1/r^2$     (C) $1/r^3$     (D) directly proportional to $r$

Two electric field lines can intersect:
(A) at a point charge     (B) at a neutral point     (C) never     (D) in a uniform field

By convention, an electrostatic test charge is always taken as:
(A) Unit positive     (B) Unit negative     (C) Large positive     (D) Large negative

Define electric field intensity at a point.

Write the formula for the electric field due to a point charge $Q$ at a distance $r$.

Define electric field lines.

Give the primary reason why electrostatic field lines do not form closed continuous loops.

What does the tangent drawn at any point on an electric field line represent?

Match the electric field concepts:

(a) Uniform electric field	(i) Net electric field intensity is zero
(b) Tangent on a field line	(ii) Parallel and equally spaced straight lines
(c) Neutral point	(iii) Gives the direction of electric field vector

The formula for electric flux through an area $\vec{A}$ in a uniform field $\vec{E}$ is $\Phi = $ ____________.

The SI unit of electric dipole moment is ____________.

The net electric flux passing through a closed cubic box enclosing an electric dipole is:
(A) $q/\epsilon_0$     (B) $2q/\epsilon_0$     (C) Zero     (D) Infinity

The torque acting on a dipole placed in a uniform electric field is maximum when the angle between $\vec{p}$ and $\vec{E}$ is:
(A) $0^\circ$     (B) $45^\circ$     (C) $90^\circ$     (D) $180^\circ$

For a short dipole, the ratio of electric field magnitudes at an axial point to an equatorial point at the same distance is:
(A) $1:1$     (B) $2:1$     (C) $1:2$     (D) $4:1$

Define electric flux. Is it a scalar or a vector quantity?

Define electric dipole moment. State its direction convention.

Write the vector expression for the torque experienced by a dipole in a uniform electric field.

Under what condition is an electric dipole in stable equilibrium in a uniform electric field?

Write the formula for the potential energy of a dipole placed in a uniform electric field.

Match the dipole formulas:

(a) Torque ($\vec{\tau}$)	(i) $-\vec{p} \cdot \vec{E}$
(b) Potential Energy ($U$)	(ii) $q(2\vec{a})$
(c) Dipole Moment ($\vec{p}$)	(iii) $\vec{p} \times \vec{E}$

The surface charge density $\sigma$ is defined as charge per unit ____________.

Gauss's law mathematically links the total electric flux to the total enclosed ____________.

What is the standard SI unit of linear charge density ($\lambda$)?
(A) $\text{C/m}^2$     (B) $\text{C/m}^3$     (C) $\text{C/m}$     (D) Coulombs

According to Gauss's Law, the electric flux out of a closed surface depends solely on:
(A) the shape of the surface     (B) the volume of the surface     (C) the net charge enclosed     (D) the position of charges inside

A Gaussian surface is essentially:
(A) Always a perfect sphere     (B) An imaginary closed surface     (C) A real metallic shield     (D) A 2D planar area

Define volume charge density ($\rho$) and write its SI unit.

State Gauss’s Law in electrostatics.

Write the integral mathematical expression for Gauss’s Law.

If a point charge $q$ is located at the center of a sphere of radius $R$, what happens to the total flux if the radius is doubled?

If a closed surface contains zero net charge, what can be said about the net electric flux leaving the surface?

Match the charge density symbols to their expressions:

(a) Linear density ($\lambda$)	(i) $Q/A$
(b) Surface density ($\sigma$)	(ii) $Q/V$
(c) Volume density ($\rho$)	(iii) $Q/L$

The magnitude of the electric field due to an infinitely long straight charged wire is proportional to ____________ (in terms of distance $r$).

The electric field produced by an infinite uniformly charged plane sheet is completely ____________ of the distance from the sheet.

What is the electric field at a point inside a uniformly charged thin spherical shell?
(A) Infinity     (B) $\sigma / 2\epsilon_0$     (C) Zero     (D) $kq/R^2$

The electric field intensity due to a uniformly charged infinite plane sheet having surface density $\sigma$ is:
(A) $\sigma / \epsilon_0$     (B) $\sigma / 2\epsilon_0$     (C) $2\sigma / \epsilon_0$     (D) Zero

For a uniformly charged spherical shell, the electric field for points outside the shell ($r > R$) behaves as if:
(A) The shell has no charge.
(B) The charge is uniformly distributed throughout the volume.
(C) The entire charge is concentrated at the center.
(D) The field is uniform everywhere.

Write the final formula for the electric field due to an infinite line charge.

Write the formula for the electric field just outside a charged conducting surface.

Write the formula for the electric field at a distance $r$ ($r > R$) outside a spherical shell of radius $R$ and total charge $Q$.

If two large parallel conducting plates carry equal and opposite surface charge densities ($\pm\sigma$), what is the electric field in the region between them?

Match the continuous charge distributions with their corresponding Electric Field magnitudes:

(a) Infinite line charge	(i) Zero
(b) Infinite plane sheet	(ii) $\sigma / (2\epsilon_0)$
(c) Inside a spherical shell	(iii) $\lambda / (2\pi\epsilon_0 r)$