Physics

Electrostatics

303 Questions

Electrostatics deals with electric charges, fields, and potentials at rest. It is a crucial topic for physics sections in engineering and civil services competitive examinations. Review these questions to build a strong understanding of Coulomb law, electric dipoles, Gauss law, and electric flux.

Electric field and potentialElectric dipole momentGauss Law applicationsCoulomb force calculationsCharge distribution on spheresEquipotential surfaces

Electrostatics Questions

Multiple choice

In electromagnetism, what is the relationship between electric field and electric potential?

  1. Electric field is the gradient of electric potential

  2. Electric potential is the integral of electric field

  3. Electric field is perpendicular to electric potential

  4. Electric potential is proportional to electric field
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In electromagnetism, the electric field is the gradient of the electric potential, which means that the electric field points in the direction of the greatest rate of change of the electric potential.

Multiple choice

In electromagnetism, what is the relationship between electric field and electric displacement?

  1. Electric field is the gradient of electric displacement

  2. Electric displacement is the integral of electric field

  3. Electric field is perpendicular to electric displacement

  4. Electric displacement is proportional to electric field
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In electromagnetism, the electric displacement is proportional to the electric field, which means that the electric displacement increases as the electric field strength increases.

Multiple choice

What is the SI unit of electric charge?

  1. Coulomb

  2. Ampere

  3. Volt

  4. Ohm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The SI unit of electric charge is the coulomb (C), which is defined as the amount of charge that flows through a conductor in one second when a current of one ampere flows through it.

Multiple choice

What is the relationship between electric field and electric potential?

  1. Electric field is the gradient of electric potential

  2. Electric potential is the gradient of electric field

  3. Electric field and electric potential are independent of each other

  4. Electric field and electric potential are inversely proportional
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electric field is the gradient of the electric potential, which means that the electric field points in the direction of the greatest rate of change of the electric potential.

Multiple choice

The photoelectric effect is the emission of electrons from a metal when light shines on it. Which of the following metals has the lowest work function?

  1. Sodium

  2. Potassium

  3. Cesium

  4. Lithium
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cesium has the lowest work function among the given metals, which means that it requires the least amount of energy to emit electrons.

Multiple choice

What is the formula for the electric force between two charges?

  1. $$F_e = kq_1q_2/r^2$$
  2. $$F_e = kq_1q_2r^2$$
  3. $$F_e = kq_1/r^2$$
  4. $$F_e = kq_2/r^2$$
  5. $$F_e = kq_1q_2r$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The formula for the electric force between two charges is $$F_e = kq_1q_2/r^2$$. Where k is the Coulomb constant, q_1 and q_2 are the charges of the two objects, and r is the distance between the two objects.

Multiple choice

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

  1. $$V = kq/r$$
  2. $$V = kq^2/r$$
  3. $$V = kq/r^2$$
  4. $$V = kq^2/r^2$$
  5. $$V = kqr$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The formula for the electric potential at a point due to a point charge is $$V = kq/r$$. Where k is the Coulomb constant, q is the charge of the point charge, and r is the distance between the point charge and the point at which the electric potential is being measured.

Multiple choice

What is the name of the constant that appears in Ampère's circuital law with Maxwell's addition?

  1. Permittivity of free space

  2. Permeability of free space

  3. Speed of light

  4. Elementary charge
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The constant that appears in Ampère's circuital law with Maxwell's addition is the permeability of free space, denoted by (\mu_0).

Multiple choice

What is the name of the constant that appears in Gauss's law for electric fields?

  1. Permittivity of free space

  2. Permeability of free space

  3. Speed of light

  4. Elementary charge
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The constant that appears in Gauss's law for electric fields is the permittivity of free space, denoted by (\epsilon_0).

Multiple choice

Gauss's Law states that the electric flux through any closed surface is proportional to the total charge enclosed by the surface. What is the proportionality constant?

  1. 1/ε0

  2. ε0

  3. 4πε0

  4. -4πε0
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The proportionality constant in Gauss's Law is 1/ε0, where ε0 is the permittivity of free space.

Multiple choice

A point charge of +1 μC is placed at the center of a spherical surface of radius 10 cm. What is the electric flux through the surface?

  1. 100 N⋅m^2/C

  2. 10 N⋅m^2/C

  3. 1 N⋅m^2/C

  4. 0.1 N⋅m^2/C
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electric flux through a spherical surface of radius r due to a point charge q at the center is given by Φ = q/ε0. Substituting the values, we get Φ = (1 μC)/(8.85 × 10^-12 C^2/Nm^2) = 100 N⋅m^2/C.

Multiple choice

A uniform electric field of 100 N/C is applied to a rectangular surface of area 0.2 m^2. What is the electric flux through the surface?

  1. 20 N⋅m^2/C

  2. 2 N⋅m^2/C

  3. 0.2 N⋅m^2/C

  4. 0.02 N⋅m^2/C
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electric flux through a surface is given by Φ = EA, where E is the electric field strength and A is the area of the surface. Substituting the values, we get Φ = (100 N/C)(0.2 m^2) = 20 N⋅m^2/C.

Multiple choice

Gauss's Law can be used to calculate the electric field of a charge distribution. What is the electric field of a uniformly charged sphere?

  1. E = kQ/r^2

  2. E = kQ/r

  3. E = kQr

  4. E = kQ/r^3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electric field of a uniformly charged sphere is given by E = kQ/r^2, where k is Coulomb's constant, Q is the total charge of the sphere, and r is the distance from the center of the sphere.

Multiple choice

Gauss's Law can be used to calculate the electric potential of a charge distribution. What is the electric potential of a point charge?

  1. V = kQ/r

  2. V = kQ/r^2

  3. V = kQr

  4. V = kQ/r^3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electric potential of a point charge is given by V = kQ/r, where k is Coulomb's constant, Q is the charge of the point charge, and r is the distance from the point charge.

Multiple choice

A hollow conducting sphere of radius R has a charge Q. What is the electric field inside the sphere?

  1. E = 0

  2. E = kQ/R

  3. E = kQ/R^2

  4. E = kQ/R^3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electric field inside a hollow conducting sphere is zero.