The Electric Field Due to a Charged Disk MCQ Quiz - Objective Question with Answer for The Electric Field Due to a Charged Disk - Download Free PDF

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Latest The Electric Field Due to a Charged Disk MCQ Objective Questions

The Electric Field Due to a Charged Disk Question 1:

An electric dipole is placed at a distance of 2 cm from an infinite plane sheet having positive charge density σ0. Choose the correct option from the following.

  1. Torque on dipole is zero and net force is directed away from the sheet. 
  2. Torque on dipole is zero and net force acts towards the sheet.
  3. Potential energy of dipole is minimum and torque is zero. 
  4. Potential energy and torque both are maximum

Answer (Detailed Solution Below)

Option 3 : Potential energy of dipole is minimum and torque is zero. 

The Electric Field Due to a Charged Disk Question 1 Detailed Solution

Calculation:

Here 

∴ The potential energy of the dipole is at a minimum, and torque is zero. 

The Electric Field Due to a Charged Disk Question 2:

A small electric dipole , having a moment of inertia I about its center, is kept at a distance r from the center of a spherical shell of radius R. The surface charge density σ is uniformly distributed on the spherical shell. The dipole is initially oriented at a small angle θ as shown in the figure. While staying at a distance r, the dipole is free to rotate about its center.

If released from rest, then which of the following statement(s) is (are) correct?

0 is the permittivity of free space.]

  1. The dipole will undergo small oscillations at any finite value of r.
  2. The dipole will undergo small oscillations at any finite value of r > R.
  3. The dipole will undergo small oscillations with an angular frequency of 
  4. The dipole will undergo small oscillations with an angular frequency of 

Answer (Detailed Solution Below)

Option :

The Electric Field Due to a Charged Disk Question 2 Detailed Solution

Calculation:

∴ 

For r = 2R

Also, for r = 10R

∴ Options 2 & 4 are correct.

The Electric Field Due to a Charged Disk Question 3:

Electric field at a distance r from an infinite thin plane sheet of uniform surface charge density σ is

  1. Inversely proportional to r
  2. Is independent of r
  3. Is independent of σ
  4. More than one of the above
  5. None of the above

Answer (Detailed Solution Below)

Option 2 : Is independent of r

The Electric Field Due to a Charged Disk Question 3 Detailed Solution

Explanation:

The electric field at a distance r from an infinite thin plane sheet of uniform surface charge density  is independent of r. The electric field due to an infinite plane sheet of charge is uniform and has a magnitude given by:

where  is the surface charge density, and  is the permittivity of free space. This electric field does not depend on the distance r from the sheet.

Thus, option '2' is correct.

The Electric Field Due to a Charged Disk Question 4:

An electron is moving under the influence of the electric field of a uniformly charged infinite plane sheet S having surface charge density +σ. The electron at t = 0 is at a distance of 1 m from S and has a speed of 1 m/s. The maximum value of σ if the electron strikes S at t = l s is α  the value of α is

Answer (Detailed Solution Below) 8

The Electric Field Due to a Charged Disk Question 4 Detailed Solution

Calculation:

Given that, 

u = 1 m/s;

t = 1 s

S = –1 m 

Using 

∴ α = 8

The Electric Field Due to a Charged Disk Question 5:

 The electric potential at the centre of two concentric half rings of radii R1 and R2, having same linear charge density λ is :

Answer (Detailed Solution Below)

Option 1 :

The Electric Field Due to a Charged Disk Question 5 Detailed Solution

Calculation: 

Electric potential due to circular arc (linear charge)

VC = V+ V2

⇒ 

⇒ 

∴ The correct answer is Option (1): 

Top The Electric Field Due to a Charged Disk MCQ Objective Questions

Calculate the electric field intensity at a distance of 10 cm from a large metallic sheet of area 400 m2. The charge of 26.55 × 10-4 C is distributed over the large metallic sheet.

  1. 1.5 × 105 N/C
  2. 1.25 × 105 N/C
  3. 2.25 × 105 N/C
  4. 3.75 × 105 N/C

Answer (Detailed Solution Below)

Option 4 : 3.75 × 105 N/C

The Electric Field Due to a Charged Disk Question 6 Detailed Solution

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CONCEPT:

  • Gauss’s Law: Total electric flux through a closed surface is 1/εo times the charge enclosed in the surface i.e. 
  • But we know that Electrical flux through a closed surface is 

Where, E = electric field, q = charge enclosed in the surface and εo = permittivity of free space.:

  • The electric field at a point due to an infinite sheet of charge is

Where ϵo = Absolute electrical permittivity of free space, E = Electric field, and σ = surface charge density. 

CALCULATION:

Given - Charge (q) = 26.55 × 10-4 C, A = 400 m2 and r = 10 cm = 10-1 m

  • The electric field at a point due to an infinite sheet of charge is

Electric field intensity due to thin infinite parallel sheets of charge in region 1 is

( a field pointing from left to right is taken as positive and the one pointing from right to left is taken as negative. )

  1. 0

Answer (Detailed Solution Below)

Option 1 :

The Electric Field Due to a Charged Disk Question 7 Detailed Solution

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CONCEPT:

  • Gauss’s Law: Total electric flux through a closed surface is 1/εo times the charge enclosed in the surface i.e. 
  • But we know that Electrical flux through a closed surface is 


Where, E = electric field, q = charge enclosed in the surface and εo = permittivity of free space.

  • The electric field at a point due to an infinite sheet of charge is


Where ϵo = Absolute electrical permittivity of free space, E = Electric field, and σ = surface charge density. 

EXPLANATION:

Let σ1 = Uniform surface density of charge on A, σ2 = Uniform surface density of charge on B, E1, E2 = Electric field intensities at a point due to charged sheet A and B respectively.

Here,  and 

 

  • The arrangement shows three regions I, II, and III.
  • We apply the superposition principle to calculate the net field intensity in the three regions. As a matter of convention, a field pointing from left to right is taken as positive and the one pointing from right to left is taken as negative


We assume, σ1 > σ> 0

In region 1:

In region 2:

In region 3:

Important Points

  • The electric field between them is given by:

The electric field due to a thin spherical shell having a charge 'q', is given as _______________, where 'r' is the distance of the point from the center of the shell, (outside the shell). ('εo' is the permittivity of free space)

  1. E = q/( 2πεor2)
  2. E = q/(4πεor)
  3. E = q/(4πεor2)
  4. E = q/(2πεor)

Answer (Detailed Solution Below)

Option 3 : E = q/(4πεor2)

The Electric Field Due to a Charged Disk Question 8 Detailed Solution

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CONCEPT:

  • Gauss Law: According to gauss’s law, total electric flux through a closed surface enclosing a charge is 1/ϵ0 times the magnitude of charge enclosed.

Where, Φ = electric flux, Qin = charge enclosed the sphere, ϵ0 = permittivity of space (8.85 × 10-12 C2/Nm2), dS = surface area

The electric field due to a thin spherical shell having a charge q:

Enclosed charge (Qin) = q

Area (S) = 4 π r2

Use Gauss' law: 

⇒ E. (S) = q/ϵ0

⇒ E.4 π r2 = q/ϵ0

Where K is a constant = 1/(4πϵ0) = 9× 109 Nm2/C2, q is charge and r is the distance from charge particle.

EXPLANATION:

The electric field due to a thin spherical shell having a charge 'q', is given as:

E = q/(4πεor2)

So option 3 is correct

The electric field at distance r from a uniformly charged infinite sheet of charge density σ will be :

  1. σ/2ϵ0
  2. σ/ϵ0
  3. σ2/2ϵ0
  4. σ20

Answer (Detailed Solution Below)

Option 1 : σ/2ϵ0

The Electric Field Due to a Charged Disk Question 9 Detailed Solution

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CONCEPT:

  • Gauss’s Law: Total electric flux through a closed surface is 1/εo times the charge enclosed in the surface i.e. 
  • But we know that Electrical flux through a closed surface is 

Where, E = electric field, q = charge enclosed in the surface and εo = permittivity of free space.

EXPLANATION:

  • The electric field at a point due to infinite sheet of charge is

Where ϵo = Absolute electrical permittivity of free space, E = Electric field, and σ = surface charge density. 

  • Thus, the field is uniform and does not depend on the distance from the plane sheet of charge. Therefore option 1 is correct.

The Electric Field Due to a Charged Disk Question 10:

Calculate the electric field intensity at a distance of 10 cm from a large metallic sheet of area 400 m2. The charge of 26.55 × 10-4 C is distributed over the large metallic sheet.

  1. 1.5 × 105 N/C
  2. 1.25 × 105 N/C
  3. 2.25 × 105 N/C
  4. 3.75 × 105 N/C

Answer (Detailed Solution Below)

Option 4 : 3.75 × 105 N/C

The Electric Field Due to a Charged Disk Question 10 Detailed Solution

CONCEPT:

  • Gauss’s Law: Total electric flux through a closed surface is 1/εo times the charge enclosed in the surface i.e. 
  • But we know that Electrical flux through a closed surface is 

Where, E = electric field, q = charge enclosed in the surface and εo = permittivity of free space.:

  • The electric field at a point due to an infinite sheet of charge is

Where ϵo = Absolute electrical permittivity of free space, E = Electric field, and σ = surface charge density. 

CALCULATION:

Given - Charge (q) = 26.55 × 10-4 C, A = 400 m2 and r = 10 cm = 10-1 m

  • The electric field at a point due to an infinite sheet of charge is

The Electric Field Due to a Charged Disk Question 11:

Electric field intensity due to thin infinite parallel sheets of charge in region 1 is

( a field pointing from left to right is taken as positive and the one pointing from right to left is taken as negative. )

  1. 0

Answer (Detailed Solution Below)

Option 1 :

The Electric Field Due to a Charged Disk Question 11 Detailed Solution

CONCEPT:

  • Gauss’s Law: Total electric flux through a closed surface is 1/εo times the charge enclosed in the surface i.e. 
  • But we know that Electrical flux through a closed surface is 


Where, E = electric field, q = charge enclosed in the surface and εo = permittivity of free space.

  • The electric field at a point due to an infinite sheet of charge is


Where ϵo = Absolute electrical permittivity of free space, E = Electric field, and σ = surface charge density. 

EXPLANATION:

Let σ1 = Uniform surface density of charge on A, σ2 = Uniform surface density of charge on B, E1, E2 = Electric field intensities at a point due to charged sheet A and B respectively.

Here,  and 

 

  • The arrangement shows three regions I, II, and III.
  • We apply the superposition principle to calculate the net field intensity in the three regions. As a matter of convention, a field pointing from left to right is taken as positive and the one pointing from right to left is taken as negative


We assume, σ1 > σ> 0

In region 1:

In region 2:

In region 3:

Important Points

  • The electric field between them is given by:

The Electric Field Due to a Charged Disk Question 12:

The electric field due to a thin spherical shell having a charge 'q', is given as _______________, where 'r' is the distance of the point from the center of the shell, (outside the shell). ('εo' is the permittivity of free space)

  1. E = q/( 2πεor2)
  2. E = q/(4πεor)
  3. E = q/(4πεor2)
  4. E = q/(2πεor)

Answer (Detailed Solution Below)

Option 3 : E = q/(4πεor2)

The Electric Field Due to a Charged Disk Question 12 Detailed Solution

CONCEPT:

  • Gauss Law: According to gauss’s law, total electric flux through a closed surface enclosing a charge is 1/ϵ0 times the magnitude of charge enclosed.

Where, Φ = electric flux, Qin = charge enclosed the sphere, ϵ0 = permittivity of space (8.85 × 10-12 C2/Nm2), dS = surface area

The electric field due to a thin spherical shell having a charge q:

Enclosed charge (Qin) = q

Area (S) = 4 π r2

Use Gauss' law: 

⇒ E. (S) = q/ϵ0

⇒ E.4 π r2 = q/ϵ0

Where K is a constant = 1/(4πϵ0) = 9× 109 Nm2/C2, q is charge and r is the distance from charge particle.

EXPLANATION:

The electric field due to a thin spherical shell having a charge 'q', is given as:

E = q/(4πεor2)

So option 3 is correct

The Electric Field Due to a Charged Disk Question 13:

The electric field at distance r from a uniformly charged infinite sheet of charge density σ will be :

  1. σ/2ϵ0
  2. σ/ϵ0
  3. σ2/2ϵ0
  4. σ20

Answer (Detailed Solution Below)

Option 1 : σ/2ϵ0

The Electric Field Due to a Charged Disk Question 13 Detailed Solution

CONCEPT:

  • Gauss’s Law: Total electric flux through a closed surface is 1/εo times the charge enclosed in the surface i.e. 
  • But we know that Electrical flux through a closed surface is 

Where, E = electric field, q = charge enclosed in the surface and εo = permittivity of free space.

EXPLANATION:

  • The electric field at a point due to infinite sheet of charge is

Where ϵo = Absolute electrical permittivity of free space, E = Electric field, and σ = surface charge density. 

  • Thus, the field is uniform and does not depend on the distance from the plane sheet of charge. Therefore option 1 is correct.

The Electric Field Due to a Charged Disk Question 14:

An electric dipole is placed at a distance of 2 cm from an infinite plane sheet having positive charge density σ0. Choose the correct option from the following.

  1. Torque on dipole is zero and net force is directed away from the sheet. 
  2. Torque on dipole is zero and net force acts towards the sheet.
  3. Potential energy of dipole is minimum and torque is zero. 
  4. Potential energy and torque both are maximum

Answer (Detailed Solution Below)

Option 3 : Potential energy of dipole is minimum and torque is zero. 

The Electric Field Due to a Charged Disk Question 14 Detailed Solution

Calculation:

Here 

∴ The potential energy of the dipole is at a minimum, and torque is zero. 

The Electric Field Due to a Charged Disk Question 15:

 The electric potential at the centre of two concentric half rings of radii R1 and R2, having same linear charge density λ is :

Answer (Detailed Solution Below)

Option 1 :

The Electric Field Due to a Charged Disk Question 15 Detailed Solution

Calculation: 

Electric potential due to circular arc (linear charge)

VC = V+ V2

⇒ 

⇒ 

∴ The correct answer is Option (1): 

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