# 24 Lecture

## Electrostatics – II

Electrostatics is a branch of physics that deals with the study of electric charges at rest. In the previous article, we discussed the basic concepts of electrostatics, Coulomb's law, electric field, and potential.

## Important Mcq's Midterm & Finalterm Prepration Past papers included

What is the unit of electric field?

a. Newtons

b. Volts

c. Teslas

d. Newtons per Coulomb

Which law relates the electric field to the electric potential?

a. Ohm's Law

b. Coulomb's Law

c. Gauss's Law

d. Ampere's Law

Which statement about electric potential is correct?

a. Electric potential is a vector quantity.

b. Electric potential is a scalar quantity.

c. Electric potential is the same as electric field.

d. Electric potential is measured in Amperes.

Answer: b. Electric potential is a scalar quantity.

Which statement about capacitance is correct?

a. Capacitance depends only on the geometry of the system.

b. Capacitance depends only on the charge on the capacitor.

c. Capacitance depends on both the geometry of the system and the dielectric constant of the material between the plates.

d. Capacitance does not depend on the voltage across the capacitor.

Answer: c. Capacitance depends on both the geometry of the system and the dielectric constant of the material between the plates.

Which of the following is true for a conductor in electrostatic equilibrium?
Which of the following is true for a conductor in electrostatic equilibrium?

a. There is no electric field inside the conductor.

b. There is no charge on the surface of the conductor.

c. The electric field is highest at the center of the conductor.

d. The potential inside the conductor is different from the potential outside the conductor.

Answer: a. There is no electric field inside the conductor.

What is the formula for the electric potential due to a point charge?

a. V = kq/r

b. V = kq/r^2

c. V = kQ/r

d. V = kQ/r^2

What is the relationship between electric potential and electric field?

a. Electric potential is proportional to electric field.

b. Electric potential is the negative gradient of electric field.

c. Electric potential is the curl of electric field.

d. Electric potential is the divergence of electric field.

Which statement about the dielectric material between the plates of a capacitor is correct?

a. The dielectric material increases the capacitance of the capacitor.

b. The dielectric material decreases the voltage of the capacitor.

c. The dielectric material increases the electric field between the plates.

d. The dielectric material decreases the energy stored in the capacitor.

Answer: a. The dielectric material increases the capacitance of the capacitor.

What is the formula for the capacitance of a parallel-plate capacitor?

a. C = ?A/d

b. C = ?d/A

d. C = ?A^2/d

What is the electric potential energy of a system of two point charges q1 and q2 separated by a distance r?

a. U = kq1q2

b. U = kq1q2/r^2

c. U = kq1q2/r

d. U = kq1^2/r + kq2^2/r

## Subjective Short Notes Midterm & Finalterm Prepration Past papers included

What is the relationship between the electric field and the electric potential?

Answer: The electric field is the negative gradient of the electric potential. E = -?V.

What is an electric dipole?

Answer: An electric dipole is a pair of opposite charges of equal magnitude separated by a distance d.

Define electric flux.

Answer: Electric flux is the number of electric field lines passing through a given surface.

What is Gauss's law?

Answer: Gauss's law relates the electric flux through a closed surface to the charge enclosed within the surface. It states that the electric flux through a closed surface is proportional to the charge enclosed within the surface.

What is meant by the term electric potential energy?

Answer: Electric potential energy is the energy associated with the position of a charged object in an electric field.

Define capacitance.

Answer: Capacitance is the ability of a system to store electrical charge.

What is an electric field?

Answer: An electric field is a region of space around a charged object in which a force would be exerted on other charged objects.

What is an electric potential?

Answer: Electric potential is the electric potential energy per unit charge.

What is the formula for the electric field between two charged plates?

Answer: E = V/d, where E is the electric field, V is the potential difference between the plates, and d is the distance between the plates.

What is the difference between conductors and insulators?

Answer: Conductors allow electricity to flow through them easily, while insulators do not. Conductors have free electrons that can move through the material, while insulators do not.

### Electrostatics – II

Electrostatics is a branch of physics that deals with the study of electric charges at rest. In the previous article, we discussed the basic concepts of electrostatics, Coulomb's law, electric field, and potential. In this article, we will discuss some more advanced topics in electrostatics, including Gauss's law, electric flux, and capacitance. Gauss's law is a fundamental law of electrostatics that relates the distribution of electric charge to the electric field. It states that the total electric flux through any closed surface is proportional to the total charge enclosed within the surface. Mathematically, Gauss's law can be expressed as: ? E · dA = Q / ?0 where E is the electric field, dA is an infinitesimal area element, Q is the total charge enclosed by the surface, and ?0 is the permittivity of free space. This law is applicable to any closed surface, irrespective of its shape, size, or orientation. Gauss's law is a powerful tool for calculating the electric field due to symmetric charge distributions. The concept of electric flux is closely related to Gauss's law. Electric flux is the measure of the flow of electric field through a surface. Mathematically, it is defined as the dot product of the electric field and the area vector of the surface. Electric flux through a surface can be expressed as: ? = ? E · dA where E is the electric field and dA is an infinitesimal area element. The SI unit of electric flux is volt-metre (V m). The total electric flux through any closed surface is proportional to the total charge enclosed by the surface, as stated by Gauss's law. Capacitance is another important concept in electrostatics. It is the ability of a system of conductors to store electric charge. The capacitance of a conductor is defined as the ratio of the magnitude of the charge on each conductor to the potential difference between them. Mathematically, capacitance can be expressed as: C = Q / V where C is the capacitance, Q is the charge stored on the conductor, and V is the potential difference between the conductors. The SI unit of capacitance is farad (F). Capacitors are devices that are used to store electric charge. They consist of two conductors, usually in the form of parallel plates, separated by a dielectric medium. Capacitance depends on several factors, including the size and shape of the conductors, the distance between them, and the dielectric constant of the medium. Capacitors have numerous applications, including energy storage, filtering, and tuning in electronic circuits. In conclusion, electrostatics is a fundamental branch of physics that has numerous applications in our daily lives. Gauss's law, electric flux, and capacitance are some of the advanced topics in electrostatics that are essential for understanding the behavior of electric charges. Capacitors are important devices that are used for storing electric charge and have widespread applications in electronic circuits.