JNTU II B.Tech I Semester Regular Examinations, November 2008
ELECTROMAGNETIC WAVES AND TRANSMISSION LINES
(Electronics & Instrumentation Engineering)
1. (a) Define potential gradient and list out salient features of potential difference.
(b) An electric dipole, 1.0ay nC-m is located at (0, 0, 0). Find out the potential
at ????1, _
4 , _
2. (a) Obtain an expression for the energy density in the field of a solenoid.
(b) Find the energy stored per unit length in the internal magnetic field of an infinite long straight wire of radii 2 mm carrying uniform current 10 A.
3. (a) Write Maxwell’s equations for free space in both point and integral form.
(b) Find D, and B if E = 10 sin (?t ? ?z) ay.
4. (a) Define direction cosine of a vector field.
(b) What are the characteristics of waves when incident normally on perfect conductor.
5. (a) Calculate the intrinsic impedance, propagation constant r and the wave veocity
? for a conducting medium in which ? = 58 Ms/m, ?r = 1 at a frequency f = 100 mHz.
(b) State the fresnel’s equations for parallel polarization and perpendicular polarization of a plane wave at OBLIQUE Incidence.
6. (a) When a wave of 6GHz propagates in parallel conducting plates separated by3cm, find the phase velocity, group velocity of the wave for the dominant wave.
(b) Write the characteristics of TEM waves.
7. (a) Explain the various primary constants for parallel wires?
(b) Calculate the characteristic impedance, the attenuation constant and phase constant of a transmission line if the following measurements have been made on the line ZOC = 550 and ZSC = 560.
8. For a typical open wire telephone cable the primary constants R = 10/km, G = 0.4×10?6mho/km, L = 0.0037H/km, C = 0.0083?F/km. Determine Zo and the propagation constant at a frequency of 1KHz.