BT-4/M-13

Field and Waves

ECE-206(E)

Time:Three Hours] [Maximum Marks:100

Unit-I

1.(a) Derive an expression for electric field of a line charge. 10

(b) Calculate D in rectangular coordinates at point P(2,-3,6) produced by

(i) a uniform line charge βlb=20C/m on the x-axis.

(ii) a uniform surface charge density βsc=120µC/m2 10

2. (a) Explain the concept of Method of Images , and derive an expression for the capacitance of two wire lines 5+5

(b) Explain Uniquenes Theorem 10

Unit-II

3.(a) Describe the force on differential current element,and prove that F=IL X B 10

(b)Consider µ=µ1=4 µH/m in the region 1 where z>o,while µ2=7 µH/m in the region 2 wherever z<0.Assume surface current K=80as A/m on the surface z=0. Given B1=2ax-3ay+az mT in the region 1. Find the value of B2. 10

4.(a) Describe Maxwell’s equation in Integral form. 10

(b) Explain the concept of force on a moving charge.5

(c) the point charge Q=18nC has a velocity of 5X106 m/s in the direction av=0.60ax+0.75ay+0.30az. Calculate the magnitude of the force exerted on the charge by the fields B=-3ax+4ay+6az mT,E=-3ax+4ay+6az acting together. 5

Unit-III

5.(a) describe the phenomenon of wave progation in Perfect dielectrics. 10

(b)explain the concept of Plane wave polarization. 10

6.(a) Explain the concept Of Skin effect and SWR.5+5

(b) The dielectric constant of pure water is 80.

(i) Determine the Brewster angle θbll for parallel polarization and the corresponding angle of transmission.5

(ii) A plane wave with perpendicular polarization is incident from air on water at θi= θbll .5

Unit-IV

7.(a) Derive transmission line equations in case of the infinite transmission line. 10

(b) A 100 MHz generator with Vg=10angle0 V and internal resistance 50 ohms is connected to a lossless 50 ohms air line that is 3.6m long and terminated in a 25+j25 ohm load. Find

(i) V(z) at a location z frm generator.

(ii) Vi at the input terminals

(iii) VSWR on the line.

(iv)Average power delivered to the load 10

8.(a) Explain TE mode concept in circular waveguides. 10

(b) A 50 ohm transmission line is connected to a load impedance ZL=35+j47.5ohm .Find the position and length of a short-circuited stub required to match the line using Smith chart.10