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

a) state and discuss ampere’s legal regulations
b) A current filament of 5.0 A in the ay direction is parallel to the y axis at x = 2m, z = -2m. obtain H at the origin.

5. a) describe and discuss Vector Magnetic Potential.
b) provided the general vector field A=5e-rcosF ar - 5cosF az in cylindrical coordinates . obtain Curl A at (2, 3? / 2, 0)
6. A circular loop of radius ‘b’ in the XY plane and carries a current ‘I’, as depicted in figure. find an expression for the magnetic flux density at a point on the positive z axis.
7. Apply Ampere’s Circuital legal regulations to the perimeter of a differential surface element and find the point form of ampere’s circuital legal regulations.

UNIT – IV
Part – A
1. Give Lorentz force formula.
2. Define torque of a force.
3. An electron in an orbit is analogous to __________.
4. What are the various kinds of materials based on their magnetic characteristics?
5. What is a diamagnetic material? provide example.
6. What is a paramagnetic material? provide example.
7. What are the classes of materials having strong atomic moments?
8. What is a ferromagnetic material? provide example.
9. What is hysterisis?
10. What is an anti ferromagnetic material? provide example.
11. What is a super paramagnetic material? provide example.
12. Define magnetization.
13. Give the magnetic boundary conditions.
14. Define inductance and provide its unit.
15. Define mutual inductance.
16. State Biot-Savart’s legal regulations.
17. State Ampere’s legal regulations.
18. What is the inductance of a toroid of circular cross section?
19. What is the torque on a solenoid?
20. State Faraday’s laws of induction.
21. What is coupling coefficient in inductors?
22. Distinguish ranging from a solenoid and a toroid.
23. State Lenz’s legal regulations.
24. Define reluctance.
Part - B

1. Give the Lorentz force formula and obtain the force on the differential current element.
2. Find the force and torque in a closed circuit.
3. Derive the magnetic boundary conditions.
4. Derive the expression for inductance and mutual inductance.
5. a) A conductor 4m long lies along the y-axis with a current of 10 A in the ay direction. obtain the force on the conductor if the field in the region is B=0.05ax T.
b) A conductor of length 2.5m located at z=0=4m carries a current of 12 A in the ay direction. obtain the uniform B in the region if the force on the conductor is 1.20*10-2 N in the direction (ax + az)/?2.
6. Find the maximum torque on an 85 turn rectangular coil, 0.2m by 0.3m, carrying current of 2.0 A in a field B = 6.5 T.
7. Find the maximum torque on an arbitrary charged particle if the charge is 1.602*10-19 C, the circular path has a radius of 0.5*10-10m, the angular velocity is 4.0*1016 rad/s and B = 0.4*10-3 T.
8. Calculate the total torque produced by the loop of dimension 1m X 2m. 1 corner of the loop lies in the origin. A field Bo = -0.6ay + 0.8 az is distributed in the loop. The loop current is 4mA.
9. Find the magnetic flux density and field intensity at appoint P due to a straight conductor of length ’l’ carrying current I.
10. Obtain the expression for the energy stored in magnetic field and energy density.
11. Find the self-inductance of a solenoid.
12. Obtain the expression for the torque experienced by a differential rectangular current loop lying in the magnetic field.
13. An air core toroid has 500 turns, a cross sectional area of 6cm2, a mean radius of 15cm and a coil current of 4A. compute magnetic field intensity. Check your ans by applying Ampere’s circuital legal regulations.

UNIT – V – Time Varying Fields
Part – A
1. Define Poynting vector. provide its unit.
2. State Poynting theorem.
3. State Faraday’s laws of electromagnetic induction.
4. Write point and integral forms of Poynting theorem.
5. What is the significance of the displacement current density?
6. Write down Maxwell’s formula corresponding to Faraday’s legal regulations in point form.
7. State Maxwell’s formula in differential and integral form corresponding to Ampere’s circuital legal regulations.
8. Write Maxwell’s formula for free space in point as well as integral form.
9. Write Maxwell’s formula in point and integral form for good conductors.
10. Compare circuit and field theory.
11. State Lenz’s legal regulations.
12. What is transformer action? What is transformer emf?
13. Explain generation action. What is generator emf?
14. If magnetic field H = [3xCos? + 6ySin?] az, obtain the current density J if the fields are invariant with time.

Part - B
1. Derive Maxwell’s formula for steady fields in point form and integral form.
2. Derive point and integral forms of Poynting theorem.
3. Compare circuit and field theory in detail.
4. Derive Maxwell’s equations in point and integral forms for time varying fields.
5. Given H = Hme j(?t+?z) ax A/m in free space. obtain E.
6. A circular loop conductor lies in plane z = 0 and has a radius of 0.1m and resistance of five ohms. provided B = 0.2 Sin 103t az, determine current in the loop.
7. a) discuss the inconsistency in Ampere’s circuital legal regulations.
(or)
discuss the displacement current density

Earning:   Approval pending.