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INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad - 500 043

Electronics and Communicaton Engineering

Question Bank

Course Name : Electromagnetic Theory and Transmission Lines (EMTL)

Course Code : A40411

Class : II - B. Tech

Branch : ECE

Year : 2014 – 2015

Course Coordinator : Mrs Usha rani

Course Faculty : G.anil reddy,seethaiah

OBJECTIVES To introduce the student to the fundamental theory and concept of electromagnetic waves and transmission lines, and their practical applications. To study the propagation, reflection, and transmission of plane waves in bounded and unbounded media. 1. Group - A (Short Answer Questions)

S. No QUESTION Blooms Taxonomy

Level Course

Outcome

UNIT-I ELECTROSTATICS

1 Define coulombs law? Remembering

1

2 find the electric field E, if the force on a stationary charge Q is F? Understanding

5

3 Define unit vector? Remembering

5

4 Specify the importance of divergence and stokes theorems? Understanding

5

5 Define gauss law? Remembering

6

6 Give the expression for the potential difference of two concentric conducting sphere of radius a and b?

Understanding

6

7 List the applications of gauss law?

Understanding

7

8 Define electric flux and give the expression? Understanding

7

9 Give the relation between electric flux and flux density ? Understanding

5

10 State the divergence theorem and give the expression ? Understanding

5

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S. No QUESTION Blooms Taxonomy

Level Course

Outcome

11 State the stokes theorem and give the expression ? Understanding

8

12 Define electric potential ? Understanding

3

13 What e is the first Maxwell’s equation ? Analysis 9

14 Give the relation between V and E? Understanding

10

15 What is the value of curl of E for a static field? Understanding

12

16 Give the expression for energy due to point Q in electricfield ? Understanding

2

17 What is the condition that the electrostatic field is conservative ? Application 7

18 What is mean by dipole moment? Understanding

6

19 Give the expression for the energy density for electrostatic fields? Understanding

5

20 Find the value of aθ.aφ ? Remembering

3

21 Define convention current density? Understanding

1

22 Define conduction current density? Understanding

5

23 List the names of few conductors along with its conductivity? Understanding

5

24 Define polarization? Understanding

5

25 Give the expression continuity equation ? Remembering

6

26 Give the expression for relaxation time? Remembering

6

27 Writ e boundary conditions for conducting media? Analysis 7

28 Writ e boundary conditions for dielectric media? Understanding

7

29 Define poission and laplace equations? Remembering

5

30 Define capacitance between two parallel plates? Analysis 5

31 What are the different types capacitors give the C value for all? Understanding

8

UNIT-II MAGNETOSTATICS

1 Define Biot severt law and give the expression? Remembering

1

2 Define amperes circuit law and give the expression? Analysis 5

3 List the applications of amperes circuit law? Understanding

5

4 What is 2nd Maxwell’s equation ? Remembering

5

5 What is 3nd Maxwell’s equation? Understanding

6

6 Define magnetic flux density? Specify the units? Remembering

6

7 Define magnetic scalar potential and give the expression? Understanding 7

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S. No QUESTION Blooms Taxonomy

Level Course

Outcome

8 Define magnetic vector potential and give the expression? Remembering

7

9 What is the value of permeability for free space and specify the units? Understanding

5

10 Lis t the types of forces exerted by the magnetic field?

Understanding

5

11 What is lenz law? Understanding

8

12 What is the Lorentz force equation for a static charge ? Understanding

3

13 What is the Lorentz force equation for a DC charge? Understanding

9

14 What is mean by magnetic dipole moment? Understanding

10

15 List the boundary conditions for Magnetic fields? Understanding

12

16 Define inductance? Remembering

7 2

17 Define mutual inductance? Understanding

7

18 What Neumann’s formula for mutual inductance? Remembering

6

19 List any two differences between self and mutual inductance? Understanding

5

20 Define magnetic energy? Remembering

1

21 Define magnetic energy due to mutual inductance? Understanding

5

22 What are the different types of magnetic materials?

Understanding

5

23 List any two differences between magnetic materials? Understanding

5

24 List any two differences between electrostatic fields and magneto static fields ?

Understanding

6

25 Define faraday law? Understanding

6

26 What is mean by transformer emf? Understanding

7

27 What is mean by generator emf? Understanding

7

28 Give the reason why amperes law is inconsistent? Remembering

5

29 Define displacement current density? Understanding

5

30 Specify the conditions for free space? Remembering 8

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S. No QUESTION Blooms Taxonomy

Level Course

Outcome

31 Specify the conditions conductor and dielectrics? Understanding

5

32 What is mean by sinusoidal harmonic variations ? Remembering

9

UNIT-III EM WAVE CHARACTERISTICS

1 What is mean by homogeneous medium? Remembering

1

2 What is mean by isotropic medium? Understanding

5

3 What is mean by linear medium? Remembering

5

4 Define uniform plane wave? Understanding

5

5 Define characteristics impedance? Remembering

6

6 Give the expression for attenuation constant? Understanding

6

7 Give the expression for phase constant?

Understanding

7

8 Define skin depth? Understanding

7

9 Define Snell’s law? Understanding

5

10 Define reflection coefficient? Understanding

5

11 Define transmission coefficient? Understanding

9

12 Define Brewster angle? Understanding

3

13 Define critical angle? Remembering

6

14 What is mean by total internal reflection? Understanding

5

15 Define surface impedance? Remembering

5

16 Define poynting theorem? Understanding

2

17 Give the expression for reflection coefficient for vertical polarization with oblique incidence?

Remembering

7

18 Give the expression for transmission coefficient for horizontal polarization with oblique incidence?

Understanding

6

19 Give the expression for reflection coefficient for normal incidence ?

Understanding

5

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S. No QUESTION Blooms Taxonomy

Level Course

Outcome

20 Give the expression for transmission coefficient for normal incidence? Understanding

2

UNIT-IV TRANSMISSION LINES- I

1 Define transmission line? Remembering

1

2 What are the types of transmission lines? Understanding

5

3 What are the primary parameters of transmission lines? Remembering

5

4 What are the secondary parameters of transmission lines? Understanding

5

5 What are the generalized equation of transmission lines? Remembering

6

6 Define characteristic impedance of a transmission lines? Understanding

6

7 Define group velocity of transmission lines?

Understanding

7

8 Specify the relation between group velocity and phase velocity of transmission lines?

Understanding

7

9 Give the condition for lossless transmission in transmission lines? Understanding

5

10 Give the condition for distortion less transmission in transmission lines? Understanding

5

11 Give the condition for maximum attenuation in transmission lines? Understanding

9

12 What is mean by line distortion in transmission lines? Understanding

3

13 What are various loads in transmission lines? Understanding

9

14 What is use of generalize transmission line equations? Understanding

9

15 What is maximum range of frequency transmission lines? Understanding

7

UNIT-V TRANSMISSION LINES- II

1 What is mean by standing wave ? Remembering

1

2 Define reflection in transmission line? Understanding

5

3 Define refraction in transmission line? Remembering

5

4 Give the expression for reflection coefficient in transmission line? Understanding

5

5 What are types of standing wave ratios in transmission line? Remembering

6

6 Specify the relation between VSWR and reflection coefficient in transmission Understanding 6

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S. No QUESTION Blooms Taxonomy

Level Course

Outcome

line?

7 Give the expression for input impedance inters of reflection coefficient ?

Understanding

7

8 What is the use of impedance transformation ? Understanding

7

9 What is mean by stub matching ? Understanding

5

10 What are the advantages of stub matching ? Understanding

5

11 What is the use of smith chart ? Understanding

3

12 What are the properties of stub matching ? Understanding

3

13 List the application of smith chart ? Remembering

6

2. Group - II (Long Answer Questions)

S. No Question Blooms Taxonomy

Level Program Outcome

UNIT-I ELETROSTATICS

1 Define divergence and divergence theorem of a vector A and write the

equations?

Remembering

5

2 Determine the divergence of T =1

r2 cos θ ar + r sin θ cos ∅ aθ + cos θ a∅?

Understanding

5

3 Define dielectric constant, dielectric strength and relaxation time in

electrostatics?

Remembering

6

4 Derive equation of continuity?

Understanding

6

5 Define curl of a vector and state Stoke’s theorem?

Remembering

7

6 Determine the curl of 𝑄 = 𝜌 sin ∅ 𝑎𝜌 + 𝜌2𝑧𝑎∅ + 𝑧 cos ∅ 𝑎𝑧? Understanding

7

7 Write a Laplacian equation on Cartesian, cylindrical and spherical

coordinates?

Understanding

5

8 Explain conduction current and derive the expression for conduction current

density?

Understanding

5

9 State coulomb’s law and write the equation for F that exist between two unlike

charges? Understanding

8

10 Derive the expression for electric field on point charge Q due to the point

charge Q1?

Understanding

3

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S. No Question Blooms Taxonomy

Level Program Outcome

11 Explain convection current density and derive expression for it?

Understanding

5

12 State Gauss’s law and obtain the firstMAXWELL’s equation for electrostatic

fields?

Understanding

8

13 What is the boundary value problem? Write steps to calculate resistance of a

conductor?

Remembering

3

14 Obtain the expression for the capacitance of a coaxial capacitor?

Understanding

1

UNIT-II MAGNETOSATICS

1 State Biot-Savart’s law and obtain the expression for magnetic field intensity

at a point P due to line current element? Remembering

5

2 State and explain Faraday’s law for time varying field? Understanding

7

3 Show that 𝛁 × 𝐄𝐦 = 𝛁 × (𝐮 × 𝐁) for time varying fields? Remembering

3

4 Define magnetic flux density? Why magnetic flux density is zero in a closed

surface?

Understanding

6

5 Show that 𝛁 × 𝐇 = 𝐉 +∂𝐃

∂t ? Remembering

7

6 State and explain ampere’s circuit law? Understanding

7

7 Obtain the expression for magnetic field intensity due to infinite line current

element?

Understanding

5

8 What is transformer emf? Show that 𝛁 × 𝐄 =− ∂𝐁

∂t Understanding

5

9 Write integral form of all MAXWELL’S equations? Understanding

7

10 Obtain Lorentz’s force equation? Remembering

3

11 Obtain the expression for force F on current element due to the magnetic field

B? Understanding

5

12 Write MAXWELL’S equations in differential form? Remembering

5

13 Show that the displacement current density 𝐉d =∂𝐃

∂t ? Understanding

7

UNIT-III EM WAVE CHARACTERISTICS

1 Derive Helmholtz equations? Remembering

5

2 State poynting theorem. What does the poynting vector represent? Understanding

5

3 Derive the relation between E and H in free space? Remembering

6

4 What is polarization? What are the different types of polarization? Understanding

3

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S. No Question Blooms Taxonomy

Level Program Outcome

5 Define conducting medium and obtain the expression for intrinsic impedance? Remembering

4

6 What is normal incidence and discuss? Understanding

9

7 Determine the reflected wave Hr, Er and the transmitted wave Et . Show that

the intrinsic impedance of the lossy medium is 𝜂 = √𝑗𝜔𝜇

𝜎+𝑗𝜔𝜀.

Understanding

5

8 Define reflection and transmission coefficient for normal incidence and write

the formulae for E? Understanding

5

9 Define Brewster angle? Obtain the expression for it? Understanding

7

10 Calculate the reflection coefficient for vertical polarization with oblique incident on perfect dielectric?

Understanding

3

11 Ensure the transmission for perfect conductor with normal incidence? Understanding

7

UNIT-IV TRANSMISSION LINES- I

1 Define a transmission line and explain the primary constants?

Understanding

2

2 What is characteristic impedance? Obtain the relation between characteristic

impedance and the propagation constant?

Remembering

5

3 Define lossless and distortion less transmission lines and write the conditions

for both?

Understanding

4

4 Obtain the input impedance of a transmission line of length l characterized by

Z0 and γ.

Remembering

3

UNIT-V TRANSMISSION LINES- II

1 Derive the expression 𝑧0 = √𝑍𝑜𝑐𝑍𝑠𝑐 .

Understanding

5

2 Explain how an open circuit line acts as a circuit element?

Remembering

5

3 Explain how a short circuit line acts as a circuit element?

Understanding

7

4 Explain the construction of smith chart?

Understanding

3

3. Group - III (Analytical Questions)

S.No QUESTIONS Blooms Taxonomy

Level Program Outcome

UNIT-I ELECTROSTATICS

1 If T =1

r3(2 cos θ ar + sin θ aθ) A/m2, calculate the current passing through a Understanding 3

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S.No QUESTIONS Blooms Taxonomy

Level Program Outcome

hemisphere shell of radius 20 cm, 0 < 𝜃 <π

2, 0 < ∅ < 2𝜋

2 Given that D = zρ cos ∅2 az C/m2, calculate the charge density at (1,π

4, 3 ) and

the total charge enclosed by cylinder of radius 1m with −2 ≤ z ≤ 2m

Understanding

9

UNIT-II MAGNETOSTATICS

1 A circular loop located on x2 + y2 = 9, z = 0 carries a direct current of 10A

along 𝒂∅. Determine H at (0, 0, 4) and (0, 0, -4)? Understanding

3

2 Given the magnetic field vector potential 𝐀 =−ρ2

4𝐚𝐳 Wb/m, calculate the total

magnetic flux crossing the surface ∅ =π

2, 1 ≤ ρ ≤ 2m, 0 ≤ z ≤ 5m?

Understanding

9

3 A parallel plate capacitor with a plate area of 5cm2and plate separation of 3mm

has a voltage 50 sin 103𝑡 V applied to its plates. Calculate displacement current

assuming ∈= 2 ∈0 ?

Understanding

9

UNIT-III EM WAVE CHARACTERISTICS

1 In a lossless dielectric for which η= 60π, 𝜇𝑟 = 1 and 𝐇 = −0.1 cos(ωt − z)𝐚𝐱 +0.5 sin(ωt − z)𝐚𝐲 A/m. Calculate 𝜀𝑟 , 𝜔 and E.

Understanding

2

2 In a non magnetic medium 𝐄 = 4 sin(2π × 107t − 0.8x)𝐚𝐳 V/m. Find𝜀𝑟, η and time average power carried by the wave?

Understanding

5

3 A plane wave propagating through a medium with 𝜀𝑟 = 8, 𝜇𝑟 = 2 has𝐄 =

0.5ez

3⁄ sin(108t − βz)𝐚𝐱. Determine the loss tangent, H field and intrinsic impedance.

Understanding 7

4 In free space, 𝐇 = 0.2 cos(ωt − βx)𝐚𝐳 A/m. Find the total power passing through a square plate of side 10cm on plane 𝑥 + 𝑦 = 1 and a circular disk of radius 5cm on plane𝑥 = 1.

Understanding

3

5 A plane wave propagating through in a non magnetic medium has 𝐄 =50 sin(108t + 2z)𝐚𝐲 V/m. Find λ, 𝜀𝑟 and H?

Understanding

7

6 In a free space(𝑧 ≤ 0), a plane wave with 𝐇 = 10 cos(108t − βz)𝐚𝐱 A/m is incident normally on a lossless medium (𝜀 = 2𝜀0, 𝜇 = 8𝜇0) in region𝑧 ≥ 0.

Understanding

2

7 For a copper coaxial cable shown below, let a= 2mm, b= 6mm and t=1mm. Calculate the resistance of a 2m length of the cable at dc and at 100 MHz?

Understanding

1

8 Given a uniform plane wave in air as 𝐄 = 40 cos(ωt − βz)𝐚𝐱 + 30 sin(ωt −βz)𝐚𝐲V/m. Find Hi, and if the wave encounters a perfectly conducting plate

normal to the z- axis at z=0, find the reflected wave Er and Hr.

Understanding

2

UNIT-IV TRANSMISSION LINES - I

1 An air line has a characteristic impedance of 70Ω and phase constant of 3rad/m

at 100 Mhz. Calculate R, C and L.

Understanding

5

2 A transmission line operating at 500 MHz has Z0=80Ω, α=0.04 Np/m, β=1.5

rad/m. Find line parameters R, L, G and C?

Understanding

4

3 A distortion less line has Z0=60Ω, α=0.04 Np/m, u=0.6c, where c is the speed of

the light in a vacuum. Find R, L and G?

Understanding

6

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S.No QUESTIONS Blooms Taxonomy

Level Program Outcome

4 A telephone line has R= 30Ω/km, L= 100mH/km, G= 0 and C=20μF/km. at f=1

KHz obtain Z0, γ and phase velocity (u).

Understanding

3

UNIT-V TRANSMISSION LINES – II

1 A certain transmission line 2m long operating at ω=106 rad/s has α=dB/m,

β=1rad/m and Z0=60+j40Ω. If the line is connected to a source of 10∟00 V, Zg=

40Ω and terminated by a load of 20+j50Ω. Determine the input Impedance and

the sending end current

Understanding

5

2 A lossless transmission line with Z0=50Ω is 30m long and operates at 2MHz. the

line is terminated with a load ZL= 60+j40Ω, if u=0.6c on the line. Find the

reflection coefficient Γ, standing wave ratio S and the input impedance Zin

Understanding

6

3 A load of 100+j150Ω is connected to a 75Ω lossless line. Find Γ, S and load

admittance YL Understanding

8

1 A certain transmission line 2m long operating at ω=106 rad/s has α=dB/m,

β=1rad/m and Z0=60+j40Ω. If the line is connected to a source of 10∟00 V, Zg=

40Ω and terminated by a load of 20+j50Ω. Determine the input Impedance and

the sending end current

Understanding

5