Electric Charges and Fields Set-1

Test your knowledge on Electric Charges and Fields from Physics, Class 12.

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Questions in this Quiz

Q1: . Two point charges placed in a medium of dielectric constant 5 are at a distance $r$ between them, experience an electrostatic force 'F'. The electrostatic force between them in vacuum at the same distance $r$ will be:

$5F$
$F$
$F/2$
$F/5$

Q2: In an experiment three microscopic latex spheres are sprayed into a chamber and became charged with charges $+3e$, $+5e$ and $-3e$ respectively. All the three spheres came in contact simultaneously for a moment and got separated. Which one of the following are possible values for the final charge on the spheres?

$+5e$, $-1e$, $+5e$
$+6e$, $+6e$, $-7e$
$-4e$, $+3.5e$, $+5.5e$
$+5e$, $-8e$, $+7e$

Q3: Two point charges $+8q$ and $-2q$ are located at $x=0$ and $x=L$ respectively. The point on $x$-axis at which net electric field is zero due to these charges is:

$8L$
$4L$
$2L$
$L$

Q4: The electric potential $V$ at any point $(x, y, z)$ is given by $V = 3x^2$ where $x$ is in metres and $V$ in volts. The electric field at the point $(1\text{m}, 0.2\text{m})$ is:

$6 \text{ V/m}$ along $(-\text{x})$-axis
$6 \text{ V/m}$ along $(+\text{x})$-axis
$1.5 \text{ V/m}$ along $(-\text{x})$-axis
$1.5 \text{ V/m}$ along $(+\text{x})$-axis

Q5: Assertion (A): On going away from a point charge or a small electric dipole, electric field decreases at the same rate in both the cases.
Reason (R): Electric field is inversely proportional to square of distance from the charge or an electric dipole.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is NOT the correct explanation of A.
A is true but R is false.
A is false and R is also false.

Q6: The electric field at $r = R$ (for a non-uniformly distributed nuclear charge $Z e$ within nucleus radius $R$) is:

directly proportional to $a$
directly proportional to $a^2$
inversely proportional to $a$
independent of $a$

Q7: The electric field within the nucleus is generally observed to be linearly dependent on $r$. This implies:

$a = 0$
$a = R/2$
$a = R$
$a = 2R/3$

Q8: Electric field intensity at point $P$ due to charge distributed over a sphere is:

$E = \frac{1}{4\pi \epsilon_0} \frac{q}{r^2}$
$E = \frac{\sigma R^2}{\epsilon_0 2r^2}$
$E = \frac{1}{4\pi \epsilon_0} \frac{2q}{r^2}$
$E = 0$

Q9: When point $P$ is inside a conducting spherical shell:

$E = 0$
$E = \frac{1}{4\pi \epsilon_0} \frac{q}{r^2}$
cannot be calculated
remains constant everywhere inside the sphere (always non-zero)

Q10: Which statement is true for Gauss's law:

All the charges whether inside or outside the gaussian surface contribute to the electric flux.
Electric flux depends upon the geometry of the gaussian surface.
Gauss's theorem can be applied to non-uniform electric field.
The electric field over the Gaussian surface remains continuous and uniform at every point.

Q11: Assertion (A): A metallic shield in form of a hollow shell may be built to block an electric field.
Reason (R): In a hollow spherical shield, the electric field inside it is zero at every point.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is NOT the correct explanation of A.
A is true but R is false.
A is false and R is also false.

Q12: A charge 'q' is placed at the center of a cube of side 'l'. What is the electric flux passing through each face of the cube?

$q / \epsilon_0$
$q / (6 \epsilon_0)$
$q / (4 \epsilon_0)$
$0$

Q13: A thin metallic spherical shell of radius $R$ carries charge $Q$. A point charge $Q/2$ is placed at its centre $C$. What is the magnitude of the force on the charge $Q/2$ at the centre?

$3Q^2 / (8\pi\epsilon_0 R^2)$
$Q^2 / (4\pi\epsilon_0 R^2)$
$Q / (4\pi\epsilon_0 R^2)$
Zero

Q14: A thin metallic spherical shell of radius $R$ carries charge $Q$. A point charge $+2Q$ is placed outside the shell at point $A$ at a distance $x$ ($x > R$) from the centre $C$. Assuming the internal charge is $Q/2$ at $C$, the force exerted by the shell and internal charge on the charge $+2Q$ at point $A$ is:

$3Q^2 / (8\pi\epsilon_0 x^2)$
$Q^2 / (4\pi\epsilon_0 x^2)$
$3Q^2 / (4\pi\epsilon_0 x^2)$
Zero

Q15: Figure shows six charged lumps of plastic coin. The cross-section of a Gaussian surface $S$ is indicated. What is the net electric flux through the surface?

$(q_1 - q_2 - q_3 - q_6) / \epsilon_0$
$(q_1 - q_2 + q_3) / \epsilon_0$
$(q_1 - q_2 + q_3 - q_6) / \epsilon_0$
$(q_1 - q_2 + q_3 - q_6 + q_4 + q_5) / \epsilon_0$

Q16: If the sizes of charged bodies are very small compared to the distances between them, we treat them as ____________.

Zero charges
Point charges
Single charge
No charges

Q17: The force per unit charge is known as ____________.

Electric current
Electric potential
Electric field
Electric space

Q18: State true or false: The total charge of the isolated system is NOT conserved.

True
False
Cannot determine
Depends on velocity

Q19: What is the dielectric constant of a metal?

$-1$
$0$
$1$
Infinite

Q20: If the charge of $1 \text{ C}$ is placed at a distance of $1 \text{ m}$ from another charge of the same magnitude in a vacuum, it experiences an electrical force repulsion of magnitude ____________.

$9 \times 10^{-9} \text{ N}$
$9 \times 10^{9} \text{ N}$
$10 \times 10^{9} \text{ N}$
$10 \times 10^{-9} \text{ N}$

Q21: The quantisation of charge indicates that

Charge, which is a fraction of charge on an electron, is not possible
A charge cannot be destroyed
Charge exists on particles
There exists a minimum permissible charge on a particle

Q22: The property which differentiates two kinds of charges is called ____________.

Equality of charge
Polarity of charge
Fraction of charge
None of the option

Q23: ————— gives the information on field strength, direction, and nature of the charge.

Electric current
Electric flux
Electric field
Electric potential

Q24: $F = k \cdot (q_1 \cdot q_2) / r^2$. This is given by which law?

Faraday’s law
Newton’s law
Coulomb’s law
Fleming’s law

Q25: From where did the term electricity get its origin?

Latin word *virtum*
Greek name *elektron*
Scientist Charles Du Fay
Scientist William Gilbert

Q26: Two charges are at distance $d$ apart in air. Coulomb force between them is $F$. If a dielectric material of dielectric constant $K$ is placed between them, the Coulomb force now becomes

$F/K$
$FK$
$F/K^2$
$K/F$

Q27: A negatively charged object $X$ is repelled by another charged object $Y$. However an object $Z$ is attracted to object $Y$. Which of the following is the most possibility for the object $Z$?

positively charged only
negatively charged only
neutral or positively charged
neutral or negatively charged

Q28: The magnitude of electrostatic force between two large conducting spheres carrying charges $Q_1$ and $Q_2$ are kept with their centres $r$ distance apart is not exactly $\frac{1}{4\pi\epsilon_0} \frac{Q_1 Q_2}{r^2}$ because

these are not point charges.
charge distribution on the spheres is not uniform.
charges on spheres will shift towards the centres of their respective spheres.
charges will shift towards the portions of the spheres which are closer and facing towards each other.

Q29: The magnitude of electric field due to a point charge $2q$, at distance $r$ is $E$. Then the magnitude of electric field due to a uniformly charged thin spherical shell of radius $R$ with total charge $q$ at a distance $r/2$ ($r \gg R$) will be

$E/4$
$2E$
$4E$
$0$

Q30: Consider an uncharged conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then,

negative and uniformly distributed over the surface of sphere
positive and uniformly distributed over the surface of sphere
negative and appears at a point on the surface of sphere closest to point charge
zero