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JNTU B.Tech II ELECTROMAGNETIC THEORY AND TRANSMISSION LINES Previous Question Paper (April/May - 2023 - R13)

B.Tech | II | II | R13 | April/May - 2023

Answer PaperPaper Code: 114CUMaximum Marks: 75Time: 3 Hours

Note: i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.

Part A

125 marks
a

What are the Two Equations of Maxwell’s for electrostatic field?

2 marks

Answer

The two Maxwell's equations for static electric fields are:

∇ · D = ρv
∇ × E = 0
b

What Electric Field Intensity and Current Density correspond to the drift velocity of 6.0 × 10⁻⁴ m/sec in a Silver Conductor?

3 marks

Answer

For silver, the mobility μ is approximately 5.6 × 10⁻³ m²/V·s. Given drift velocity vd = 6.0 × 10⁻⁴ m/s, the Electric Field Intensity E is:

E = vd / μ = (6.0 × 10⁻⁴) / (5.6 × 10⁻³) ≈ 0.107 V/m

Using J = σE, where conductivity σ for silver is 6.17 × 10⁷ S/m:

J = (6.17 × 10⁷) × 0.107 ≈ 6.6 × 10⁶ A/m²
c

State Biot-Savart’s Law.

2 marks

Answer

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d

Define magnetic flux density.

3 marks

Answer

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e

What is Brewster’s Angle?

2 marks

Answer

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f

Obtain the characteristic impedance of free space.

3 marks

Answer

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g

Draw the T – type equivalent circuit of a transmission line.

2 marks

Answer

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h

What is Propagation Constant?

3 marks

Answer

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i

State the applications of smith chart.

2 marks

Answer

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j

Sketch the input impedance of a lossless line for shorted and open circuited conditions.

3 marks

Answer

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Part B

210 marks
a

State and explain Coulomb’s law.

5 marks

Answer

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b

The capacitance of the conductor formed by the two parallel metal sheets, each 100cm², in area separated by a dielectric 2mm thick is, 2×10⁻¹⁰ micro farad with a potential of 20KV is applied to it. Find (i) Electric flux (ii) Potential gradient in kV/m (iii) The relative permittivity of materials (iv) Electric flux density.

5 marks

Answer

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OR
310 marks
a

Derive Convection and Conduction Current with necessary equations.

5 marks

Answer

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b

Obtain the poisson’s and Laplace equations in electro static fields.

5 marks

Answer

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410 marks
a

Describe how the inconsistency in Ampere’s Law is rectified by Maxwell.

5 marks

Answer

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b

An infinitely long conductor of radius 𝒂 is placed such that its axis is along the z-axis. The vector magnetic potential, due to a dielectric current 𝐼₀ flowing along 𝒂𝒛 in the conductor is given by

𝐴⃗ = −(𝐼₀ / 4πa²)μ₀(x² + y²)𝒂𝒛 Wb/m
. Find the corresponding 𝐻⃗.

5 marks

Answer

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OR
510 marks
a

State and explain Faraday’s laws for time varying magnetic fields.

5 marks

Answer

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b

In free space

𝐷⃗ = Dm sin(ωt + βz)𝒂𝒛
. Using Maxwell’s equations, show that
𝐵⃗ = −(ωμ₀Dm / β) sin(ωt + βz)𝒂𝒚
.

5 marks

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610 marks
a

Derive the expression for the attenuation constant, phase constant and intrinsic impedance for a uniform plane wave in a good conductor.

5 marks

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b

If εr = 11, μ=μ₀ for the medium in which a wave with frequency f= 0.8GHz is propagating, determine propagation constant and intrinsic impedance of the medium when i) σ = 0 and ii) σ = 20 mho/m.

5 marks

Answer

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OR
710 marks
a

State and explain Poynting theorem.

5 marks

Answer

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b

A plane wave travelling in air is normally incident on a material with μr = 2 and εr = 6. Find the reflection and transmission coefficients.

5 marks

Answer

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810 marks
a

Derive the relationship between secondary constant and primary constants of a transmission line.

5 marks

Answer

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b

A high frequency line has the following primary constants L=1.5 mH/Km, C=0.07μF/Km, R = G = negligible. Determine the characteristics impedance and propagation constant of the Line.

5 marks

Answer

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OR
910 marks
a

Derive the secondary constant equations from basic transmission lines.

5 marks

Answer

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b

A lossy cable which has R = 4.25 Ω/m, L = 3.0 μH/m, C = 2 pF/m, and G = 0 operates at f = 0.5 GHz. Find the attenuation constant of the line.

5 marks

Answer

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1010 marks
a

Define reflection coefficient of a transmission line and derive the expression for it.

5 marks

Answer

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b

A low loss transmission line of 100 Ω characteristic impedance is connected to a load of 400 Ω. Calculate the Reflection Coefficient and Standing wave ratio.

5 marks

Answer

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OR
1110 marks
a

Discuss in detail about Double Stub Matching.

5 marks

Answer

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b

A 100Ω loss less line connects a signal of 100 KHz to load of 140 Ω. The load power is 100mW. Calculate (i) Voltage reflection coefficient (ii) VSWR (iii) Position of Vmax, Imax, Vmin and Imin.

5 marks

Answer

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This page contains the question paper of ELECTROMAGNETIC THEORY AND TRANSMISSION LINES from JNTU for B.Tech ECE II II, April/May - 2023, R13.

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