SRM University 2007 B.Tech Electronics and Communications Engineering Bank : Electromagnetic Field Theory - Question Paper

7. In the case of a 2 concentric spherical shell capacitor, the radii of the 2 spheres differ by four cm, and the capacitance of the spherical conductor is 53.33 Pico farad. If the outer sphere is earthed, compute the radius, assuming air as dielectric.
8. Obtain the boundary conditions on the interface of a dielectric and a conductor.
9. Vector current density is provided by
J = (4/r2 )Cos?ar + 20e-2rSin?a? – rSin?Cos?a? A/m2.
a) obtain J at r=3, ?=0 and ?=?.
b)Find the total current passing through the spherical cap r=3, o
10. State and discuss Uniqueness theorem.
11. Current density is provided by J = (1/r) e-t ar A/m2. At t = 1s, compute total outward current in a cylinder if r = 5m and also obtain the velocity with which the J moves at arbitrary radius ‘r’ (‘r’ = radius of cylinder).

UNIT III - STEADY MAGNETIC FIELD
PART A

1. State Biot Savart legal regulations
2. State Stokes Theorem
3. State Ampere’s Circuital legal regulations.
4. Define Magnetic flux density
5. Define Magnetic Field Intensity and provide its relation with magnetic flux density.
6. State the Gauss legal regulations for Magnetic Field.
7. State Magnetic Field formula due to finite length current element


8. Explain vector magnetic potential
9. Write down the expression fro energy density of magnetic field
10. What is the point form of Ampere’s Circuital Law?
11. State the concept of curl.
12. Write down Maxwell’s formula for Steady magnetic Field.
13. What is Scalar Magnetic Potential?
14. Given the general vector field A = (y cosax) ax + (y+ex) az .Find curl A at the origin.
15. Define X A of cylindrical coordinates
16. Given the general vector field A = 10sin? a?, in spherical coordinates obtain curl A at (2, ? / 2, 0)
17. Give the expression of the vector magnetic field for current filament, sheet current and quantity current.
18. Distinguish scalar and Vector Magnetic Potential.

PART B

1. Calculate field using Ampere’s Circuital legal regulations for infinitely long solenoid
2. Determine the Magnetic flux density B caused by a finite length current filament of length ‘L’ on the z-axis at a distance ‘d’ from the origin.
3. Explain how to compute field using Ampere’s Circuital legal regulations for symmetrical current distribution for infinitely long filament carrying current I
4. Explain how to compute field using Ampere’s Circuital legal regulations for symmetrical current distribution for coaxial cable.

Earning:   Approval pending.