JNTU II B.Tech I Semester Regular Examinations, November 2008
ELECTROMAGNETIC WAVES AND TRANSMISSION LINES
(Electronics & Instrumentation Engineering)
1. (a) Define potential at a point and obtain its expression.
(b) The potential at a point A is 10 volts and at B is 15 volts. If a charge, Q =10 ?C is moved from A to B, what is the work required to be done.
2. (a) Explain the coefficient of coupling in an inductor coil.
(b) Two coils of L1 = 100 mH, L2 = 50 mH have a coefficient of coupling equal to 0.3. Find mutual inductance.
3. (a) Obtain Maxwell’s equations in phasor form.
(b) Verify whether the following fields E = 2 sin x sin t ay and H = 2?0 cos x cos t az satisfy the Maxwell’s equation in free space.
4. (a) Derive an expression for reflection of a wave when incident on dielectric with oblique incidence with perpendicular polarization.
(b) Explain the concept of total internal reflection.
5. (a) Derive the expression for power flow in a concentric cable?
(b) A parallel polarized wave propagates from air to a dielectric at Brewster angle
of 75 degrees. Find ?r.
6. (a) Explain the field equations for TE waves in rectangular wave guide. Define dominant mode.
(b) If a wave of 6GHz is propagating between two parallel conducting plates sepa-
rated by 30mm, find the cut-off wavelength, guide wavelength for TE10 mode.
7. Obtain the expression for current and voltage at any point along a line which is terminated in Zo.
8. (a) Explain briefly properties of smith chart?
(b) A lossless transmission line of length 100m has an inductance of 28?H and a capacitance of 20nF. Find propagation velocity, phase constant at an operating frequency of 100kHz and characteristic impedance of the line.