## Exam Questions in Electrical Engineering; time-varying electrical currents

Radoje Jankovic, borrowed these questions from a friend.

**I already posted a lot of my original questions a few years ago
with and without answers. **

1. The condition under which the laws of Kirhof apply.

2. The influence of the shape of the conductors to which the elements are interconnected to the current strength in the branches at time varying currents.

3. The notion of quasi-stationarity of the network.

4. Kirhof’s laws for time-varying networks.

5. Power in networks with time-varying currents.

6. Basic concepts of periodic and prostoperiodic quantities (period, frequency, amplitude, circular frequency, current and initial phase).

7. Concept of phase difference of two prostoperiodic quantities.

8. Mean of periodic quantities.

9. Effective value of periodic quantities.

10. Basic and higher harmonics of the signal. Undesirable effects of higher harmonics.

11. Production of electromotive force (emf)

12. Role of Transformation in the Transmission and Distribution of Electricity.

13. Production of high frequency prostoperiodic voltages.

14. Determination of the current through basic passive elements connected to the periodic voltage.

15. Representation of prostoperiodic quantities using rotational vectors (example).

16. Power in networks with prostoperiodic currents (active and reactive and power factor).

17. Active and reactive receivers.

18. Kirhof’s laws for electric networks with prostoperiodic currents in algebraic form.

19. Translating Kirhof equations from algebraic to complex form.

20. Number of unknowns and number and types of equations for solving a network with prostoperiodic currents.

21. Impedance and Admittance (Real and Imaginary Parts and Their Units)

22. Regular, Parallel and Mixed Connections of Elements.

23. The equivalence of the relation of elements to a star and a triangle.

24. Representation of complex voltages and currents in a complex plane.

25. Voltage and current generators.

26. Contour current method in complex form.

27. Node potential method in complex form.

28. Complex Consumer (Receiver) and Generator Power.

29. Superposition theorem in complex form.

30. The reciprocity theorem in complex form.

31. Tevenen’s and Norton’s theorem in complex form.

32. Compensation theorem in complex form.

33. Maintenance theorem of complex and instantaneous power.

34. Adjusting the receiver to the generator.

35. Repair of receiver power factor.

36. Free resonant (regular) circuit.

37. Free anti-resonant (parallel) circuit.

38. Electric networks with magnetically coupled branches.

39. Ideal transformer theory.

40. Transformer in linear operating mode (wiring diagram and basic equations).

41. Equivalent Tevenen generator with respect to transformer secondary connections.

42. Transformer input impedance.

43. Autotransformer.

44. Three Phase Rotary Generators.

45. Connection of a three-phase generator winding into a star (term and relation between phase and interphase voltages).

46. Connection of a three-phase generator winding into a triangle (term and relation between phase and interphase voltages).

47. Load (Receiver) connection for three-phase generators.

48. Analysis of a symmetrical three-phase star-connected load.

49. Analysis of a symmetric three-phase receiver connected to a triangle.

50. Power of three-phase loads and generators.

51. Comparison of three-phase and single-phase power transmission systems.

52. Production of a rotating magnetic field by a two-phase current system.

53. Production of a rotating magnetic field by means of a symmetric three-phase current system.