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KONGUNADU COLLEGE OF ENGG. & TECH., THOLURPATTI-621215 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING ACADEMIC YEAR 2011-2012 ODD SEMESTER II YEAR EEE – QUESTION BANK EE1201 ELECTROMAGNETIC THEORY 2 mark Questions Unit 1 Fundamentals 1. What are the sources of electromagnetic field? 2. State the effects of emf 3. State the different types of coordinate systems 4. State the difference between the three coordinate systems 5. How to convert Cartesian to cylindrical system? 6. How to convert Cartesian to spherical system? 7. How to convert spherical to Cartesian system? 8. How to convert cylindrical to Cartesian system? 9. Find the distance between the points A(2,3,-1) and B(4,50º,2) 10. Find the distance between the points A(2,3,-1) and B(4,25º,45º) 11. Transform the Cartesian coordinate (2,1,3) into spherical coordinate. 12. Find the vector A directed from (2,-4,1) to (0,-2,0) in Cartesian coordinates and also find the unit vector along A. 13. Transform the following vector to cylindrical coordinate at the point specified. 5āx at (4,120º,2) 14. Develop the equation for a volume of a sphere of radius ‘a’ from the differential volume. 15. Define a vector field with example 16. Define a scalar field with example

17. Define line integral of a vector field 18. Define a surface integral of a vector field 19. Define a volume integral of a vector field 20. What is a solenoidal vector? 21. What is a irrotational vector? 22. Define divergence 23. State divergence theorem 24. Define curl 25. State Stoke’s theorem 26. What is gradient? Big Questions Unit 1: 1. 2. 3. 4. 5. 6.

Explain the transformation between the cartesian and cylindrical systems Explain the sources and effects of electromagnetic fields State and prove the divergence theorem State and Prove Stokes theorem State and prove divergence Using the divergence theorem evaluate ∫∫F.n ds where F = 2xy i + y2 j + 4y2 k where s is the cube of x=y=z= 0 to 1.

Unit 2 Electrostatics 1. What do you understand by absolute permittivity? 2. State coulomb’s law 3. State coulomb’s law in vector form 4. Define electric field intensity 5. State the principle of superposition in coulomb’s law

6. If the electric field is 100 V/m at a distance of 2m from a point charge of q, then find q at free space. 7. Define volume charge density 8. Define surface charge density 9. Define linear charge density 10. State the difference between electric potential and potential difference 11. Define absolute potential 12. State the relationship between electric field and potential. 13. Find the electric field intensity at a distance of 20cm from a charge of 2µC in vacuum. 14. Find the electric flux density at a distance of 20cm from a charge of 2µC in vacuum. 15. Find the electric potential at a point (4,3)m due to a charge of 1nC located at the origin in free space. 16. A uniform spherical volume charge distribution contains a total charge of 10-8C if the radius of this spherical volume is 2cm. Find the volume charge density. 17. Determine the potential difference between the points a and b which are at a distance of 0.5m and 0.1m respectively from a negative charge of 2x10-10 C 18. Define Dipole 19. Define Dipole moment 20. Define electric flux density. 21. State Gauss’s Law 22. Find the electric field at the centre of the square which is having side ‘a’. 23. Find the potential at the centre of the square which is having side ‘a’ 24. State the applications of Gauss’s Law 25. Calculate the electric field at any point using electric dipole concept.

26. State Poission’s Equation 27. State Laplace’s Equation 28. Define Polarization 29. Define capacitance 30. Define energy density 31. State the boundary conditions for the electric fields 32. Define electric current 33. State ohm’s law in point form 34. Define one farad 35. A parallel plate air core capacitor is floating with 20V across the plates. If the thickness of the plates are increased into double the original value, calculate the new voltage across the capacitor. 36. Calculate the current density for the copper wire which is having a conductivity of 5.8x10 7 S/m and the field intensity of 10V/m 37. Calculate the energy stored by the electric field for the field intensity of 100V/m. 38. The capacitance of a parallel plate capacitors with two parallel plate metal sheets each 100cm 2 in area, separated by a dielectric 2 mm thickness is 2x10-4 microfarad. A potential difference of 20KV is applied find the total dielectric flux. 39. Find the energy density for the given potential V=3x + 4y in free space.

BIG QUESTIONS Unit 2: 1. 2. 3. 4. 5. 6. 7. 8.

State and prove Gauss’s law(6) Derive the equation for energy stored in a capacitor Derive the equation for potential due to dipole arrangement Four positive point charges 10-9 C each are situated in X –Y plane at points (0,0), (0,1), (1,0) and (1,1) m. Fine the electric field intensity and electric potential at a point (1/2,1/2)m. Derive the equation for electric field intensity for a straight uniformly charged conductor which is having a length of l meters. Derive the capacitance for single phase transmission line. Derive Poisson’s equations. Explain the boundary conditions in electric fields

9. 10.

If V=20/(x2+y2) then find E Derive the equation for electric field intensity for a circular disc which is having a radius of a meters.

Unit 3 Magnetostatics 1. Define Magnetic Field Intensity 2. Define Magnetic Flux density 3. State Biot-Savart’s Law 4. State Ampere’s Law for current element 5. Define Solenoid 6. Derive the expression for the field intensity at the centre of the square coil whose side is ‘a’ which is placed in XY plane. 7. Derive the field intensity at the centre of the semicircular loop. 8. A wire carrying a current of 100A is bent into a square form of 10cm side. Calculate the field intensity and flux density at the centre of the coil. 9. A wire carrying a current of 100A is bent in the form of circular coil of dia 10cm. Calculate the flux density at the centre of the coil. 10. A wire carrying a current of 100A is bent in the form of circular coil of dia 10cm. Calculate the flux density at the point on the axis of the coil 12 cm from it. 11. State Ampere’s Circuital law. 12. A circular coil of radius 10cm is made up of 100 turns. It carries a current of 5 ampere. Find the field intensity at the centre. 13. Calculate the magnetic flux density due to a circular coil of 100 A turns and area 70cm2 on the axis of the coil at a distance 10cm from the centre. 14. A round copper conductor is carrying a current of 250A. Determine the magnetizing force and flux density at a distance of 10cm from the conductor. 15. State Lorentz law of force.

16. Define torque. 17. Determine the force per meter length between two long parallel wires A and B separated by 5cm in air and carrying currents of 40 amperes in the same direction. 18. Define magnetic moment 19. The loop has 10 cm side and carries a current of 3 ampere. Find the magnetic moment. 20. What do you understand by magnetic vector potential? 21. The magnetic vector potential in the XY plane is given by A = (ey cosx)i +(1+sin2x)k. Calculate the flux density at the origin. 22. Define inductance 23. What is mutual inductance? 24. Define coefficient of coupling 25. What is diamagnetic material? 26. What is paramagnetic material? 27. What is ferromagnetic material? 28. Compare the three types of magnetic materials 29. Define magnetic dipole 30. Define magnetic dipole moment 31. Define magnetization 32. State the boundary conditions for the magnetic fields 33. Define Solenoid and toroid. 34. An inductive circuit is carrying a current of 4 amp. If its inductance is 0.15H. Find the value of the self induced emf when the current is reduced to zero in 0.01 second. 35. Two coils having self inductance of 1mH and 2mH and the mutual inductance of 0.5mH are connected in series. Find effective inductance of series combination when the current is reversed. 36. Find the energy density for the given potential V=3x + 4y in free space.

37. Calculate the inductance of the solenoid of 200 turns wound on a cylindrical tube of 6 cm diameter. The length of the tube is 60cm and the medium is air. 38. Calculate the inductance of a ring shaped coil having a mean diameter of 20cm wound on a wooden core of 2cm diameter. The winding is uniformly distributed and contains 200 turns. 39. A coil has a self inductance of 1H and a resistance of 4 ohms. It is connected to a 40V DC supply. Estimate the energy stored in the magnetic field when the current has attained its final steady value.

BIG QUESTIONS Unit 3: 1. 2.

Derive the equation for magnetic field intensity for a finite length of conductor Derive the magnetic field intensity at any point along the axis of the solenoid. 3. Explain about the magnetic vector potential 4. Explain about the magnetic boundary conditions 5. Derive the force between two current carrying wires 6. Derive the equation for energy and energy density in the magnetic field. 7. Derive the inductance of two wire transmission line which are having solid inner conductors 8. Evaluate the inductance of a solenoid of 2500 turns wound uniformly over a length of 0.5m on a cylindrical paper tube 4cm in dia. The medium is air. 9. Derive the equation for magnetic field intensity for a circular disc.

Unit 4 Electro Dynamic Fields 1. Define Conduction Current 2. Define conduction current density 3. Define displacement current 4. Define displacement current density 5. State Faraday’s Law 6. Write the Maxwell’s equations from Ampere’s law 7. Write the Maxwell’s equations from Faraday’s law 8. Write the Maxwell’s equations from Gauss’s law

9. A coil of 500 turns is linked by a flux of 0.4mwb. If the flux is reversed in 0.01 seconds find the emf induced in the coil. 10. Calculate the displacement current through a parallel plate air filled capacitor having plates of 10cm2 separated by a distance of 2mm and connected to a 360V, 1KHz source. BIG QUESTIONS: Unit 4 : 1. 2. 3. 4. 5.

Derive the Maxwell’s equations in point form and integral form Using transmission lines, compare the circuit theory and field theory Derive the equation for Conduction current density State and prove Poynting theorem Derive the equation for displacement current density

Unit 5 ELECTROMAGNETIC WAVES 1. Define Wave 2. Write the wave equation in electric field 3. Write the wave equation in magnetic field 4. Write the wave equation in free space 5. State the relationship between velocity of light and permeability 6. State the conditions for uniform plane waves 7. What are TEM waves? 8. Define characteristic impedance or intrinsic impedance 9. Find the intrinsic impedance for free space 10. State the maxwell’s equation in phasor form 11. State the wave equations in Phasor form 12. Write the wave equation for conducting medium

13. What do you understand by the propagation constant? 14. Write Helmholtz equation 15. State the condition to check the dielectric, lossy dielectric and conductor 16. What do you understand by lossy dielectric? 17. Find the phase shift constant at 1MHz frequency. 18. Find the attenuation constant of free space when the conductivity is 5.8x10-3S/m 19. Define skin depth or depth of penetration 20. Calculate the skin depth for free space when the frequency is 100Hz and conductivity is 5.8x103 S/m. 21. Define polarization 22. State the different types of polarization 23. What is linear polarization? 24. What is elliptical polarization? 25. What is circular polarization? 26. State the law of reflection 27. State Snell’s law 28. State the law of frequency 29. What do you understand by normal incidence? 30. What do you understand by oblique incidence? 31. State the difference between normal and oblique incidence. 32. State the types of oblique incidence 33. Define vertical polarization 34. Define perpendicular polarization

35. Define reflection coefficient 36. Define transmission coefficient 37. Calculate the reflection coefficient for the dielectric material which is having relative permeability of 10 and permittivity of 5 38. Calculate the transmission coefficient for the dielectric material which is having relative permeability of 10 and 15 and permittivity of 5 and 10 39. Calculate the reflection coefficient of free space when relative permittivity is 10 and 20 40. Calculate the transmission coefficient of free space when the relative permittivity is 10 and 20. 41. Define Brewster angle 42. Find the conducting behavior of a ground at 1KHz at the conductivity of 5x10-3S/m and permittivity of 10. 43. A parallel polarized wave is incident from air into paraffin. Find the Brewster angle assuming permittivity of paraffin to be 2. 44. Define Poynting Vector with an example. 45. State Poynthing theorem 46. Write the power flow equation per unit volume using pointing theorem 47. What is standing wave ratio?

BIG QUESTIONS: Unit 5: 1. 2. 3. 4. 5. 6.

Derive the wave equation in electric and magnetic field Derive the equation for intrinsic impedance (i) Derive Helmholts equation from wave equation Derive the attenuation constant from Helmholtz equation Derive the propagation constant for lossy dielectrics and good conductor Explain about the reflection of plane waves by a perfect conductor.