JNTU
JNTU B.Tech III ELECTROMAGNETIC FIELDS AND WAVES Previous Question Paper (March - 2021 - R18)
Answer any five questions
All questions carry equal marks
Main
Define electric field intensity at a point. Derive the expression for E of a line charge.
Answer
Electric field intensity (E) at a point is defined as the force experienced by a unit positive test charge placed at that point in an electric field. It is expressed as E = F/q, where F is the force and q is the charge.
To derive the electric field due to an infinite line charge with uniform charge density ρL (C/m) along the z-axis, consider a Gaussian cylinder of radius r and length L centered on the z-axis. By Gauss's Law:
The surface integral consists of the top, bottom, and curved side surfaces. Since E is radial, the flux through the top and bottom surfaces is zero. For the curved surface:
Solving for E:
Find E due to infinite surface charge distribution by using gauss’s law.
Answer
Consider an infinite sheet of charge in the xy-plane with uniform surface charge density ρS (C/m2). By symmetry, the electric field must be directed normal to the sheet (along the z-axis).
Construct a Gaussian pillbox extending above and below the sheet, with cross-sectional area A. The flux passes only through the two end caps of the pillbox:
The enclosed charge is Qenclosed = ρSA. Applying Gauss's Law:
Simplifying for E:
where an is the unit vector normal to the surface.
Establish Poisson’s and Laplace’s equations from Gauss’s law.
Answer
Sign in to view the complete answer paper.
State and Explain Biot-Savart’s law. Derive the magnetic field produce at a point due to an infinite line current distribution.
Answer
Sign in to view the complete answer paper.
Derive general wave equations. Write wave equations for free-space conditions and conducting medium conditions.
Answer
Sign in to view the complete answer paper.
Explain “Inconsistency of Ampere’s law”.
Answer
Sign in to view the complete answer paper.
A plane wave propagating through a medium with εr = 10, μr = 2 has E = 0.5 e-z/3 sin(108t – βz) ax V/m. Determine i) Phase constant ii) the loss tangent iii) intrinsic impedance iv) Wave velocity v) H field.
Answer
Sign in to view the complete answer paper.
Define the reflection coefficient and derive the expression for input impedance in terms of reflection coefficient.
Answer
Sign in to view the complete answer paper.
A uniform plane wave is incident normally on a plane surface separating two lossless dielectric media. Discuss quantitatively the phenomenon that takes place.
Answer
Sign in to view the complete answer paper.
Explain the polarization of a plane wave.
Answer
Sign in to view the complete answer paper.
Explain the solution of wave equation in a rectangular waveguide.
Answer
Sign in to view the complete answer paper.
Discuss the properties and characteristics of waveguide.
Answer
Sign in to view the complete answer paper.
What is the connection between Faraday’s law of induction and the magnetic force?
Answer
Sign in to view the complete answer paper.
Explain Dominant and Degenerate Modes in detail.
Answer
Sign in to view the complete answer paper.
Derive the conditions of the boundary between Dielectric-Dielectric interface.
Answer
Sign in to view the complete answer paper.
State and prove Poynting theorem.
Answer
Sign in to view the complete answer paper.