Inductors, Capacitors, and AC Circuits: Basics and Applications

1. CHAPTER 2 INDUCTORS, CAPACITORS AND ALTERNATING CURRENT

2. LEARNING OUTCOMES • Upon completion of this chapter, students should be able to: • apply basic principles of inductors, capacitors and AC circuits • solve the combination problems

3. CONTENTS • Inductors • Capacitors • AC basic circuits • R-L, R-C, R-L-C circuits

4. INDUCTORS • Also known as choke or coil – has characteristics against the change of the current • 2 types of inductors used: • Fixed type Variable type

5. Unit : Henry • Symbol : L • Inductors – spiral coil of wire that creates magnetic field when current passes through it

6. inductors • The magnetic field is directed from left to right and is highly intensified • The changing in magnetic field gives interesting properties that known a inductance • Increase the current will expand the field that generates the emf in the coil

7. INDUCTORS • The generated emf is opposes the applied voltage • The effects of inductors in the circuit: • Smooth wave ripples in the DC circuit • Improve the transmission characteristics of waves in the telephone line

8. INDUCTANCE 2 types: • Self inductance (L) • Mutual inductance (M)

9. SELF INDUCTANCE (L) • Occurs when a current flow in the coil causing the changing of flux in the winding • EMF generates due to : • The changing of magnetic flux • The changing of current

10. SELF INDUCTANCE (L) L = N · , So : Where; L = Self inductance N = Number of turns = Flux change against time = Current change against time L = N

11. MUTUAL INDUCTANCE (M) • The ability of a first coil to produce 1 emf • in the nearest coil through induction or • when the current in the first coil is changing

12. MUTUAL INDUCTANCE (M) • How they work?? • When current flow in the first loop, flux will be produce in the first coil • The continuous current causes flux flow to the next coil and then generate emf in the second coil • Emf produced in second coil will cut the conductor and produce the voltage in second loop

13. Series inductors Total inductance = sum of all values of inductance in the circuit

14. PARALLEL inductors Total inductance =

15. inductors Example : Calculate the total inductance (LT) for the three coil when the value of each inductor is 0.02H, 44mH, 400 μHif the connection is in: • Series • Parallel

16. Inductive reactance, • Inductive reactance = the opposition to the current flow • Unit : Ω • Value of Inductive reactance depends on the inductance of the circuit due to the current change in the circuit

17. Inductive reactance, Where; = Inductive reactance (Ω) f = Frequency (Hz) L = Inductor (Henry) = 2fL

18. Inductive reactance, Example : A coil with 0.2H connected with AC 200V, 50Hz. Calculate the inductive reactance in the circuit

19. Energy in Inductor Unit : Joule (J) E = LI²

20. A coil of 0.75H is supplied with 3A current. Calculate the energy in the circuit.

21. capAcitor • Use : store electrical energy (charge) • Unit : Farad (F) • Symbol : C

22. capAcitor • Capacitor or condenser built with two-conductors or plates arranged opposite each other • They are separated by insulator (dielectric)

23. capAcitor • 2 plates  a plate has negative charge (-ve)  a plate has positive charge (+ve)

24. capAcitor • Effect of capacitor in the circuit: • Increasing the circuit power factor • Reducing the fireworks during the switch is on inside the circuit • Reduce radio interference test in the starter circuit pendaflour light • Strengthen the electric current • Store electrical charges

25. capacitance • Capacitance = Quantity or amount of electric charge needed to make difference between two plates where, Q = Charge V = Voltage C =

26. capacitance • 3 factors affect the value of capacitance • Area of plate, A • Distance between 2 plates, d • Permeability, ε

27. capacitance • Area of the plate, A - Capacitance is directly proportional to the cross sectional area of the plates. - Capacitance of a capacitor varies with the capacitor plate area. - Area of large plates to accommodate many electrons and can save a lot of charge C µA

28. capacitance • Distance between two plates, d - Capacitance is inversely proportional to the distance between the plates. • Capacitance of a capacitor change when the distance between the plates changes. • Capacitance will increase when the plate is brought closer and less-plates removed. C µ

29. capacitance • Permeability, ε - Capacitance is proportional to the permeability of the conductor C µ ε

30. Series capacitors =

31. Series capacitors • It also can be; =

32. Series capacitors • The charge for each capacitor; Where,

33. Series capacitors Capacitance, C = • Voltage drop for each capacitor is = =

34. Series capacitors = OR =

35. Series capacitors Voltage drop for each capacitor = =

36. Series capacitors Example Two capacitors each value is 6μF and 10μF is connected in series with a 200V power supply. Calculate: • Total capacitance • Charge in each capacitor • Voltage across each capacitor

37. parallel capacitors

38. parallel capacitors • Voltage drop at each capacitor is equal • Charge can be calculated as

39. Example Calculate the total capacitance of the three capacitors where the value of each capacitance is 120μF when it is connected in: • Series • Parallel

40. CAPACITANCE reactance, • Capacitance reactance = opposition to the flow of current • Unit : Ω where

41. CAPACITANCE reactance, SO where = Capacitance reactance (Ω) f = Frequency (Hz) C = Capacitor (F) ω = Angular velocity ()

42. CAPACITANCE reactance, Example 8μF capacitor connected to the supply of 240V, 50Hz. Calculate the value of capacitance reactance.

43. Energy in capacitor Unit : Joule (J) E = QV

44. Energy in capacitor Example Capacitor with 8pF connected to the 600V power supply. Calculate the charge and energy that can be stored by the capacitor.