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2023 102101

B.Tech. 1st Semester Examination, 2023

Time 03 Hours
Full Marks 70
Instructions:
  • The marks are indicated in the right-hand margin.
  • There are NINE questions in this paper.
  • Attempt FIVE questions in all.
  • Question No. 1 is compulsory.
  • Symbols used (if any) have their usual meanings.

Q.1 Choose the correct answer of the following (Any seven question only):

Q1.1

The curl of electric field is

a)

always zero

b)

never zero

c)

sometimes zero

d)

undefined

Q1.2

Faraday cage protects from lightning strike because the cage material is

a)

very strong

b)

conducting so it grounds the electricity

c)

conducting so it shields electromagnetic waves

d)

none of the above

Q1.3

Magnetic monopoles do not exist because

a)

they are extremely difficult to find

b)

the magnetic field is solenoidal

c)

monopoles become stable at extremely low temperatures

d)

electric field is much stronger than magnetic field

Q1.4

Ampere’s law is incomplete because

a)

it was discovered many years ago

b)

it is incompatible with the law of conservation of charge

c)

it is valid only for time dependent currents

d)

it is incompatible with the solenoidal nature of magnetic field

Q1.5

Which of the following is true

a)

Maxwell’s equations are valid only for electrostatics

b)

The divergence of magnetic field is zero only in magnetostatics

c)

Maxwell’s equations hold only in empty space

d)

Maxwell’s equations are valid under all circumstances

Q1.6

For a constant magnetic field $ \vec{B} = B_0 \vec{k} $ the vector potential $ \vec{A} $ is

a)

0

b)

B0(yi^+xj^)/2B_0 (-y \hat{i} + x \hat{j})/2

c)

B0(yi^+xj^)/2B_0 (y \hat{i} + x \hat{j})/2

d)

B0(xi^+yj^)/2B_0 (x \hat{i} + y \hat{j})/2

Q1.7

If you put a Dielectric slab between the plates of a parallel plate capacitor

a)

The electric field inside increases

b)

The capacitance increases

c)

The capacitance decreases

d)

The potential difference between plates increases

Q1.8

Magnetic susceptibility of diamagnetic material is

a)

Positive

b)

Negative

c)

Zero

d)

None of above

Q1.9

Lenz’s law is consequence of the law of conservation of

a)

Charge

b)

Energy

c)

Momentum

d)

Mass

Q1.10

Which of the following is not true about the electromagnetic waves

a)

They are transverse in nature

b)

Electric field is perpendicular to magnetic field

c)

Electric field is parallel to propagation vector K\mathbf{K}

d)

Magnetic field is perpendicular to propagation vector K\mathbf{K}

Q.2 Solve all parts :

Q2.1

Show that (i) electrostatic field is always normal to the surface of a conductor and (ii) electrostatic potential is always constant inside conductor.

Q2.2

If $ \vec{E} = a (y\hat{\mathbf{i}} - x\hat{\mathbf{j}}) $ show if this electrostatic field can exist or not.

Q2.3

The electric field E in the x-y plane is given by $ \vec{E} = 2cx\hat{\mathbf{i}} + ay\hat{\mathbf{j}} $, where c and a are constant, what is the charge density responsible for this field?

Q.3 Solve both questions :

Q3.1

A spherical conductor contain a uniform surface charge density $\sigma$ determine the field and potential due to charge distribution.

Q3.2

State Gauss’s law of electrostatics. Derive differential form of Gauss’s law.

Q.4 Solve all parts :

Q4.1

Obtain detailed boundary conditions on the electric field and electric displacement.

Q4.2

What is electric dipole? Define its dipole moment.

Q4.3

Find expression for the field and potential due to electric dipole.

Q.5 Solve both questions :

Q5.1

Write brief technical notes on ferromagnetic, paramagnetic and diamagnetic material.

Q5.2

What is magnetic vector potential? A current distribution gives rise to magnetic vector potential, $\vec{A}(x,y,z) = x^2y\hat{\mathbf{i}} + y^2x\hat{\mathbf{j}} - xyz\hat{k}$, find the magnetic field at $(-1,2,3)$.

Q.6 Solve all parts :

Q6.1

Derive the expression for the energy stored in a magnetic field.

Q6.2

Starting from the Faraday’s law obtain its differential form. Establish the equivalence of Faraday’s law and motional emf.

Q6.3

State and discuss Lenz’s law.

Q.7 Solve both questions :

Q7.1

Obtain the continuity equation for charge and use it to modify Ampere’s law to include displacement current.

Q7.2

State and derive Poynting’s theorem.

Q.8 Solve both questions :

Q8.1

Derive the electromagnetic wave equation in vacuum. Prove the transverse nature of plane wave.

Q8.2

For a plane wave given as $ \vec{E}(\vec{x},t) = A \sin(\vec{k}.\vec{\mathbf{x}} - \omega t)$ find (i) the magnetic field (ii) direction of propagation (iii) Poynting vector and (iv) the energy density.

Q.9 Solve both questions :

Q9.1

Starting with general Maxwell’s equation derive Maxwell’s equation in a linear medium with permittivity $\epsilon$ and permeability $\mu$.

Q9.2

Write a technical note on the Method of Images. Mention the significance of uniqueness theorem as a basis for the method.


2023 V4 102101

B.Tech. 1st Semester Examination, 2023

Time 03 Hours
Full Marks 70
Instructions:
  • The marks are indicated in the right-hand margin.
  • There are NINE questions in this paper.
  • Attempt FIVE questions in all.
  • Question No. 1 is compulsory.
  • Symbols used (if any) have their usual meanings.

Q.1 Choose the correct answer of the following (Any seven question only):

Q1.1

The curl of electric field is

a)

always zero

b)

never zero

c)

sometimes zero

d)

undefined

Q1.2

Faraday cage protects from lightning strike because the cage material is

a)

very strong

b)

conducting so it grounds the electricity

c)

conducting so it shields electromagnetic waves

d)

none of the above

Q1.3

Magnetic monopoles do not exist because

a)

they are extremely difficult to find

b)

the magnetic field is solenoidal

c)

monopoles become stable at extremely low temperatures

d)

electric field is much stronger than magnetic field

Q1.4

Ampere’s law is incomplete because

a)

it was discovered many years ago

b)

it is incompatible with the law of conservation of charge

c)

it is valid only for time dependent currents

d)

it is incompatible with the solenoidal nature of magnetic field

Q1.5

Which of the following is true

a)

Maxwell’s equations are valid only for electrostatics

b)

The divergence of magnetic field is zero only in magnetostatics

c)

Maxwell’s equations hold only in empty space

d)

Maxwell’s equations are valid under all circumstances

Q1.6

For a constant magnetic field $ \vec{B} = B_0 \vec{k} $ the vector potential $ \vec{A} $ is

a)

0

b)

B0(yi^+xj^)/2B_0 (-y \hat{i} + x \hat{j})/2

c)

B0(yi^+xj^)/2B_0 (y \hat{i} + x \hat{j})/2

d)

B0(xi^+yj^)/2B_0 (x \hat{i} + y \hat{j})/2

Q1.7

If you put a Dielectric slab between the plates of a parallel plate capacitor

a)

The electric field inside increases

b)

The capacitance increases

c)

The capacitance decreases

d)

The potential difference between plates increases

Q1.8

Magnetic susceptibility of diamagnetic material is

a)

Positive

b)

Negative

c)

Zero

d)

None of above

Q1.9

Lenz’s law is consequence of the law of conservation of

a)

Charge

b)

Energy

c)

Momentum

d)

Mass

Q1.10

Which of the following is not true about the electromagnetic waves

a)

They are transverse in nature

b)

Electric field is perpendicular to magnetic field

c)

Electric field is parallel to propagation vector K\mathbf{K}

d)

Magnetic field is perpendicular to propagation vector K\mathbf{K}

Q.2 Solve all parts :

Q2.1

Show that (i) electrostatic field is always normal to the surface of a conductor and (ii) electrostatic potential is always constant inside conductor.

Q2.2

If $ \vec{E} = a (y\hat{\mathbf{i}} - x\hat{\mathbf{j}}) $ show if this electrostatic field can exist or not.

Q2.3

The electric field E in the x-y plane is given by $ \vec{E} = 2cx\hat{\mathbf{i}} + ay\hat{\mathbf{j}} $, where c and a are constant, what is the charge density responsible for this field?

Q.3 Solve both questions :

Q3.1

A spherical conductor contain a uniform surface charge density $\sigma$ determine the field and potential due to charge distribution.

Q3.2

State Gauss’s law of electrostatics. Derive differential form of Gauss’s law.

Q.4 Solve all parts :

Q4.1

Obtain detailed boundary conditions on the electric field and electric displacement.

Q4.2

What is electric dipole? Define its dipole moment.

Q4.3

Find expression for the field and potential due to electric dipole.

Q.5 Solve both questions :

Q5.1

Write brief technical notes on ferromagnetic, paramagnetic and diamagnetic material.

Q5.2

What is magnetic vector potential? A current distribution gives rise to magnetic vector potential, $\vec{A}(x,y,z) = x^2y\hat{\mathbf{i}} + y^2x\hat{\mathbf{j}} - xyz\hat{k}$, find the magnetic field at $(-1,2,3)$.

Q.6 Solve all parts :

Q6.1

Derive the expression for the energy stored in a magnetic field.

Q6.2

Starting from the Faraday’s law obtain its differential form. Establish the equivalence of Faraday’s law and motional emf.

Q6.3

State and discuss Lenz’s law.

Q.7 Solve both questions :

Q7.1

Obtain the continuity equation for charge and use it to modify Ampere’s law to include displacement current.

Q7.2

State and derive Poynting’s theorem.

Q.8 Solve both questions :

Q8.1

Derive the electromagnetic wave equation in vacuum. Prove the transverse nature of plane wave.

Q8.2

For a plane wave given as $ \vec{E}(\vec{x},t) = A \sin(\vec{k}.\vec{\mathbf{x}} - \omega t)$ find (i) the magnetic field (ii) direction of propagation (iii) Poynting vector and (iv) the energy density.

Q.9 Solve both questions :

Q9.1

Starting with general Maxwell’s equation derive Maxwell’s equation in a linear medium with permittivity $\epsilon$ and permeability $\mu$.

Q9.2

Write a technical note on the Method of Images. Mention the significance of uniqueness theorem as a basis for the method.


2022 102101

B.Tech 1st Semester Exam-2022

Time 03 Hours
Full Marks 70
Instructions:
  • The marks are indicated in the right-hand margin.
  • There are NINE questions in this paper.
  • Attempt FIVE questions in all.
  • Question No. 1 is compulsory.
  • Symbols used (if any) have their usual meanings.

Q.1 Answer any seven of the following:

Q1.1

Define electric polarization.

Q1.2

Write down Laplace’s equation.

Q1.3

Define displacement current.

Q1.4

What is the physical interpretation of bound charges?

Q1.5

Define diamagnetism. Give two examples of diamagnetic materials.

Q1.6

With necessary expression, explain standing wave ratio.

Q1.7

What do you mean by skin effect?

Q1.8

Explain the terms motional e.m.f. and transformer e.m.f.

Q1.9

Differentiate between conduction and convection current.

Q1.10

What is meant by retarded potential?

Q.2 Solve both questions :

Q2.1

Find the electric field at a distance $ z $ above the centre of a circular loop (radius R) carrying uniform linear charge $ \lambda $.

Q2.2

Write down the expression for electric field due to surface charge distribution of volume charge density $ \rho $.

Q.3 Solve this question :

Q3.1

Derive the expression for Transmission coefficient of electromagnetic waves from a non-conducting medium–vacuum interface for normal incidence.

Q.4 Solve both questions :

Q4.1

A point charge $ q $ is situated at a distance a from the centre of a grounded conduction sphere of radius R. Using the method of images, find the potential outside the sphere.

Q4.2

Explain Faraday cage? What is the electrical force inside a Faraday cage when it is struck by lightning?

Q.5 Solve both questions :

Q5.1

Derive continuity equation for current densities.

Q5.2

State and derive Poynting theorem.

Q.6 Solve both questions :

Q6.1

Derive the boundary conditions for electrostatic field intensity and electric flux density at (i) the interface between two dielectrics and (ii) the interface between a perfect conductor and a dielectric.

Q6.2

A long spherical cloud of radius $ r $ has a uniform volume charge distribution of $ \rho_v $. Calculate the potential distribution and the electric field at any point in space using Poisson’s and Laplace’s equations.

Q.7 Solve both questions :

Q7.1

A solenoid of radius 4 mm and length 2 cm has 150 turns/m and carries current 500 mA. Find- (i) $ |H| $ at the centre (ii) $ |H| $ at the ends of the solenoid.

Q7.2

Determine whether the following potential equations satisfy Laplace's equation or not: (i) $ V = 2x^2 - 4y^2 + z^2 $ (ii) $ V = r^2 \cos \phi + \theta $.

Q.8 Solve both questions :

Q8.1

State Ampere's circuit law. Write its application.

Q8.2

A hollow conducting cylinder has inner radius a and outer radius b and carries current I along the positive z-direction. Find H everywhere.

Q.9 Write short notes on any two of the following:

Q9.1
a)

Transverse nature of electromagnetic waves propagating in vacuum

b)

Energy carried by electromagnetic waves

c)

Electromagnetic braking and its application

d)

Electric field due to electric dipole


2022 V2 102101

B.Tech 1st Semester Exam-2022

Time 03 Hours
Full Marks 70
Instructions:
  • The marks are indicated in the right-hand margin.
  • There are NINE questions in this paper.
  • Attempt FIVE questions in all.
  • Question No. 1 is compulsory.
  • Symbols used (if any) have their usual meanings.

Q.1 Answer any seven of the following:

Q1.1

Define electric polarization.

Q1.2

Write down Laplace’s equation.

Q1.3

Define displacement current.

Q1.4

What is the physical interpretation of bound charges?

Q1.5

Define diamagnetism. Give two examples of diamagnetic materials.

Q1.6

With necessary expression, explain standing wave ratio.

Q1.7

What do you mean by skin effect?

Q1.8

Explain the terms motional e.m.f. and transformer e.m.f.

Q1.9

Differentiate between conduction and convection current.

Q1.10

What is meant by retarded potential?

Q.2 Solve both questions :

Q2.1

Find the electric field at a distance zz above the centre of a circular loop (radius R) carrying uniform linear charge λ\lambda.

Q2.2

Write down the expression for electric field due to surface charge distribution of volume charge density ρ\rho.

Q.3 Solve this question :

Q3.1

Derive the expression for Transmission coefficient of electromagnetic waves from a non-conducting medium–vacuum interface for normal incidence.

Q.4 Solve both questions :

Q4.1

A point charge qq is situated at a distance a from the centre of a grounded conduction sphere of radius R. Using the method of images, find the potential outside the sphere.

Q4.2

Explain Faraday cage? What is the electrical force inside a Faraday cage when it is struck by lightning?

Q.5 Solve both questions :

Q5.1

Derive continuity equation for current densities.

Q5.2

State and derive Poynting theorem.

Q.6 Solve both questions :

Q6.1

Derive the boundary conditions for electrostatic field intensity and electric flux density at (i) the interface between two dielectrics and (ii) the interface between a perfect conductor and a dielectric.

Q6.2

A long spherical cloud of radius rr has a uniform volume charge distribution of $ \rho_v $. Calculate the potential distribution and the electric field at any point in space using Poisson’s and Laplace’s equations.

Q.7 Solve both questions :

Q7.1

A solenoid of radius 4 mm and length 2 cm has 150 turns/m and carries current 500 mA. Find- (i) H|H| at the centre (ii) H|H| at the ends of the solenoid.

Q7.2

Determine whether the following potential equations satisfy Laplace's equation or not: (i) $ V = 2x^2 - 4y^2 + z^2 (ii)(ii) V = r^2 \cos \phi + \theta $.

Q.8 Solve both questions :

Q8.1

State Ampere's circuit law. Write its application.

Q8.2

A hollow conducting cylinder has inner radius a and outer radius b and carries current I along the positive z-direction. Find H everywhere.

Q.9 Write short notes on any two of the following:

Q9.1
  • Transverse nature of electromagnetic waves propagating in vacuum
  • Energy carried by electromagnetic waves
  • Electromagnetic braking and its application
  • Electric field due to electric dipole
a)

Transverse nature of electromagnetic waves propagating in vacuum

b)

Energy carried by electromagnetic waves

c)

Electromagnetic braking and its application

d)

Electric field due to electric dipole


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