Electrostatics Basics

39 Questions

What is produced by a charge moving with constant velocity (Variable E, zero a)?

Both Electric and Magnetic field but no radiations

What is the SI unit of charge?

Coulomb (C)

Which of the following factors does Coulomb's constant (k) depend upon?

System of units and medium between charges

What happens to the electrostatic force between two point charges if the distance between them is doubled?

It becomes one-fourth as strong

What is the charge of an electron?

-1.6 x 10^-19 C

Which condition maximizes the electrostatic force between two point charges?

Minimum distance between the charges

Which method of charging involves the transfer of electrons by direct contact?

Conduction

In which unit system is Coulomb's constant $k$ equal to 1?

CGS unit system

If a charge is at rest, what does it produce?

Only Electric field

Which of the following statements about Coulomb's law is not true?

It is valid in the presence of other charges.

Which of the following tools can detect and measure electric charges?

Electrometer

What is the value of Coulomb's constant $k$ in S.I units?

9 × 10⁹ Nm²C⁻²

Which of the following factors does NOT affect the value of Coulomb's constant?

Magnitude of charges

What is the dimensional formula of Coulomb's constant?

[ML³T⁻⁴A⁻²]

What happens to the force between two charges if a non-conducting material is introduced between them?

The force decreases.

Coulomb’s law is valid for which of the following scenarios?

Point charges in free space

Which of the following best describes the dielectric constant?

Ratio of force in free space to force in a medium

Which of the following occurs as the distance between two charges increases?

The force between them decreases.

Given the value of the permittivity of free space, $ ext{8.85} imes 10^{-12} ext{ C}^2/ ext{Nm}^2$, compute the force between two point charges of $+1 ext{C}$ each, separated by a distance of $1 ext{m}$ in a vacuum.

9 × 10⁹ N

What happens to the force between two charges when a dielectric medium with a relative permittivity $ε_r$ is completely filled between them?

The force decreases by a factor of $ε_r$

Which of the following is correct about the validity of Coulomb's Law?

It is valid for stationary and point charges

What is the dielectric constant for water (distilled)?

What will be the force between two charges if a metal is inserted between them?

The force becomes zero

Which material has a relative permittivity within the range of 4-10?

Bakelite

If the distance between two charges is $r$, under what condition is Coulomb's Law applicable?

When $r ≥ 10^{-15}$ m

What does it imply if the relative permittivity $ε_r$ of a material is infinite?

The material is a metal

Calculate the force between two charges in a medium with a relative permittivity $ε_r$ if the force in vacuum is $F$.

$rac{F}{ε_r}$

Which of the following statements about electric charge is correct?

Charge on a proton is opposite in sign to that on an electron

In which scenario does an accelerated charge not radiate energy?

When V is constant and a = 0

What is the quantized minimum charge value for an electron?

1.6 x 10^-19 C

Which unit is used to measure electric charge?

Coulomb

If an atom loses electrons, what happens to its mass?

Mass decreases

Which condition produces only an electric field, but no magnetic field or radiation?

V = 0 and a = 0

What is the numerical value of $k$ in SI units?

$9 imes 10^9$ N·m²/C²

What is the dimensional formula of the absolute permittivity of air or free space ($ ext{ε}_o$)?

[ML$^{3}$T$^{-4}$A$^{2}$]

Which graph represents the relationship between the electrostatic force $F$ and the product of the charges $q_1q_2$?

Straight Line (F vs $q_1q_2$)

In Coulomb’s Law, if the distance between two charges is doubled, how does the electrostatic force between them change?

It reduces to one-fourth

What is the force on $q_2$ due to $q_1$ in vector form according to Coulomb's law?

$rac{k ext{ } q_1 q_2}{r^2} (-f{ ext{r}}_{12})$

Which pair of graphs correctly represents the functional dependence of $F$ on $1/r^2$ and $r^2$?

Steeper than the others (F vs 1/$r^2$) and Hyperbola (F vs $r^2$)

Study Notes

Electrostatics

Electrostatics is the study of charges at rest.
Charge is a scalar property of matter that produces and experiences electrical and magnetic effects.
Charge is conserved, and it is always associated with mass.
When an atom loses or gains electrons, its mass decreases or increases, respectively.

Electric Charges

There are two types of electric charges: positive and negative.
Like charges repel each other, while opposite charges attract each other.
The SI unit of electric charge is the Coulomb (C).
Charge is quantized, meaning it comes in discrete packets, and the charge on a proton is equal to the negative of the charge on an electron.

Accelerated Charge Radiates Energy

An accelerated charge radiates energy in the form of electromagnetic waves.
When a charge is at rest, it produces an electric field (E) only.
When a charge is moving with a constant velocity, it produces both electric and magnetic fields (E and B), but no radiation.
When a charge is accelerated, it produces time-varying electric and magnetic fields, which radiate energy.

Coulomb's Law

Coulomb's law states that the electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
The force is given by the equation F = k * q1 * q2 / r^2, where k is Coulomb's constant.
Coulomb's constant (k) depends on the system of units and the medium between the charges.
In SI units, k = 1 / (4 * π * εo), where εo is the absolute permittivity of free space.

Electric Potential

Electric potential is the potential energy per unit charge at a given point in space.
Electric potential is a scalar quantity.

Energy Stored in a Capacitor

A capacitor is a device that stores energy in the electric field between two conductors.
The energy stored in a capacitor is given by the equation U = (1/2) * Q * V, where Q is the charge and V is the voltage.

Electric Field

Electric field is a vector field that surrounds charged particles.
Electric field is responsible for the force experienced by a test charge.
Electric field is given by the equation E = F / q, where F is the force and q is the charge.

Capacitors and Capacitance

Capacitors are devices that store energy in the electric field between two conductors.
Capacitance is the ability of a capacitor to store charge.
Capacitance is given by the equation C = Q / V, where Q is the charge and V is the voltage.

Charging and Discharging of Capacitors

Charging a capacitor involves transferring charge from one conductor to another.
Discharging a capacitor involves transferring charge from the capacitor to another conductor.

Methods of Charging

Friction: Charging by rubbing two materials together.
Conduction: Charging by touching a conductor to another conductor.
Induction: Charging by bringing a conductor near a charged object.

Learn about the fundamental principles of electrostatics, including electric charges, their properties, and behavior. Understand the concepts of charge conservation, quantization, and the relationship between charge and mass.

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