JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III Year ELECTROMAGNETIC THEORY AND TRANSMISSION LINES Previous Question Paper (March - 2024 - R16)

B. Tech | III Year | I Semester | R16 | March - 2024

Answer PaperPaper Code: 135APMaximum Marks: 75Time: 3 Hours

Note: Part A is compulsory (25 Marks). Answer all questions. In Part B, answer any one question from each unit (10 Marks each).

Part A

Answer all questions:

25 marks

Define Gauss law.

2 marks

Answer

Gauss's law states that the total electric flux Ψ passing through any closed surface is equal to the total charge Q enclosed by that surface.

Ψ = ∮ D · dS = Q

What is the significance of relaxation time?

3 marks

Answer

Relaxation time (τ) is the time required for a charge placed in the interior of a material to decay to 1/e (approximately 36.8%) of its initial value due to conduction. It is defined as:

τ = ε / σ

Its significance lies in distinguishing between conductors and dielectrics: for good conductors, τ is extremely small, meaning charge dissipates almost instantly, whereas for good dielectrics, τ is very large, meaning charge remains for a long duration.

Define scalar potential.

2 marks

Answer

What are the applications of Amperes circuital law?

3 marks

Answer

What is a dielectric?

2 marks

Answer

What is the importance of polarization?

3 marks

Answer

Define loading of a transmission line.

2 marks

Answer

What is the importance of characteristic impedance?

3 marks

Answer

What is OC line?

2 marks

Answer

What is the importance of VSWR?

3 marks

Answer

Part B

210 marks

Derive the expression for the capacitance of parallel plate capacitor.

5 marks

Answer

A positive charge is placed at (0,0,0) and an equal negative charge is placed at (10,0,0). Compare the potentials at points (0,0,0), (4,0,0), (8,0,0) and (10,0,0).

5 marks

Answer

310 marks

What is continuity equation? Describe in detail.

5 marks

Answer

A conducting plane is located at z = 0 in free space, and a 30-nC point charge is present at (2, 5, 7). If the potential at z = 0 is zero, find the potential at (10, 5, 3).

5 marks

Answer

410 marks

What are the Maxwell’s equations for magnetostatic fields? Explain.

5 marks

Answer

Two parallel circular loops of radii 10 m and 5 m, are coaxially located and carry currents 2 A and 1 A respectively. Find the force between the loops if the axial distance between the centers of the loops is (i) 50 m (ii) 100 m.

5 marks

Answer

510 marks

What is Faraday’s law? Explain.

5 marks

Answer

A coil of negligible dimensions of 1000 turns has the shape of regular polygon of 8 sides inscribed in a circle of radius 10m. Find the magnitude of flux density at the center of the coil when it carries a current of 5 A per turn.

5 marks

Answer

610 marks

Discuss in detail about the wave propagation in good dielectrics.

5 marks

Answer

In a transmission line filled with a lossless dielectric (ϵ = 4.5ϵo, μ = μo) with the following expression, find H and the Poynting vector.

5 marks

Answer

710 marks

State and explain Poynting theorem.

5 marks

Answer

The magnetic field component of a plane wave in a lossless dielectric is given below. Calculate the wavelength, wave velocity, wave impedance and polarization.

5 marks

Answer

810 marks

Derive the expression for characteristics impedance of transmission line.

5 marks

Answer

A microstrip line is 1 cm thick and 1.5 cm wide. The conducting strip is made of brass (σc = 1.1×107 S/m) while the substrate is a dielectric material with ϵr = 2.2 and tanϴ = 0.002. If the line operates at 2.5 GHz, find Zo and ϵeff.

5 marks

Answer

910 marks

What is the condition for minimum attenuation? Explain.

5 marks

Answer

A 50-Ω microstrip line has a phase shift of 450 at 8 GHz. If the substrate thickness is h = 8 mm with ϵr = 4.6, find width of the conducting strip and the length of the mictrostrip line.

5 marks

Answer

1010 marks

What is smith chart? What are its applications?

5 marks

Answer

A transmission line is terminated by a load with admittance YL = (0.6+j0.8)/Zo. Find the normalized input impedance at λ/6 from the load.

5 marks

Answer

1110 marks

Explain the significance of Zmin and Zmax.

5 marks

Answer

What is λ/4 line? Explain in detail.

5 marks

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III Year ELECTROMAGNETIC THEORY AND TRANSMISSION LINES Previous Question Paper (March - 2024 - R16)

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Part B

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