1. Physics Chapter 20: Circuits and Circuit Elements

2.  Schematic  Diagram of an Electric Circuit  Uses Symbols to Represent Elements within the Circuit +- R1R1 R2R2

3. Circuits and Circuit Elements  Schematics  Some Standard Symbols  Conductor  Switch  Fuse

4. Circuits and Circuit Elements  Schematics  Some Standard Symbols  Capacitor  Resistor  Potentiometer

5. Circuits and Circuit Elements  Schematics  Some Standard Symbols  Ground  Battery  Generator +- +-

6. Circuits and Circuit Elements  Schematics  Some Standard Symbols  Connection  No Connection

7. Circuits and Circuit Elements  Series Wiring +- R1R1 R2R2

8. Circuits and Circuit Elements  Series Wiring  More than One Device Connected to a Voltage Source  Provides the Same Electric Current Through Each Device

9. Circuits and Circuit Elements  Series Wiring  Current Flow Interrupted at One Device Will Prevent Current from Reaching the Other Device + - R1R1 R2R2 I

10. Circuits and Circuit Elements  Series Wiring  The Voltage Supplied by the Power Source is Divided Among the Devices Used in the Circuit + - R1R1 R2R2 I V1V1 V2V2

11. Circuits and Circuit Elements  Series Wiring  The Resistance to the Circuit Voltage is the Sum of the Device Resistance  Equivalent Resistance in Series (R s ) + - R1R1 R2R2 I V1V1 V2V2

12. Circuits and Circuit Elements  Series Wiring  So… + - R1R1 R2R2 I V1V1 V2V2 and

13. Circuits and Circuit Elements  Parallel Wiring +- R1R1 R2R2

14. Circuits and Circuit Elements  Parallel Wiring  More than One Device Connected to a Voltage Source  Provides the Same Electric Voltage Through Each Device

15. Circuits and Circuit Elements  Parallel Wiring  Current Flow Interrupted at One Device Will NOT Prevent Current from Reaching the Other Device +- R1R1 R2R2 I1I1 I2I2 I

16. Circuits and Circuit Elements  Parallel Wiring  Voltage is the Same at Each Resistor  Current is Divided Among the Devices Present in the Circuit +- R1R1 R2R2 I1I1 I2I2 I

17. Circuits and Circuit Elements  Parallel Wiring  Since I=V/R and Voltage is Constant +- R1R1 R2R2 I1I1 I2I2 I

18. Circuits and Circuit Elements  Parallel Wiring  R p – Equivalent Resistance in Parallel +- R1R1 R2R2 I1I1 I2I2 I

19. Circuits and Circuit Elements  Parallel Wiring  So… +- R1R1 R2R2 I1I1 I2I2 I

20. Circuits and Circuit Elements  Problem:  A current of 1.2 A is measured through a light bulb when it is connected across a 120V source. What power is dissipated by the bulb?

21. Circuits and Circuit Elements  Solution:  V = 120V  I = 1.2 A  P = ?

22. Circuits and Circuit Elements  Problem:  A 12V automobile battery is connected to an electric starter motor. The current through the motor is 210A. How many joules of energy does the battery deliver to the motor each second, and what power, in watts, does the motor use?

23. Circuits and Circuit Elements  Solution:  V = 12V  I = 210 A  P = ?

24. Circuits and Circuit Elements  Problem:  A flashlight bulb is connected across a 3.0V potential difference. The current through the lamp is 1.5A. What is the power rating of the lamp, and how much electric energy does the lamp use in 11 minutes?

25. Circuits and Circuit Elements  Solution:  V = 3.0V  I = 1.5 A  P = ?

26. Circuits and Circuit Elements  Problem:  What voltage is applied to a 4.0  resistor if the current is 1.5 A?

27. Circuits and Circuit Elements  Solution:  I = 1.5 A  R = 4.0   V= ?

28. Circuits and Circuit Elements  Problem:  A voltage of 75V is placed across a 15  resistor. What is the current through the resistor?

29. Circuits and Circuit Elements  Solution:  R = 15.0   V= 75V  I = ?

30. Circuits and Circuit Elements  Problem:  The graph in shows the current through a device called a silicon diode. A potential difference of +0.70 V is placed across the diode. What resistance would be calculated?

31. Circuits and Circuit Elements  Solution:  V = 0.70V  I = 0.022A  R = ?

32. Circuits and Circuit Elements  Problem:  Draw a series circuit diagram to include a 16  resistor, a battery, and an ammeter that reads 1.75 A. Conventional current is measured through the meter from left to right. Indicate the positive terminal and the voltage of the battery.

33. Circuits and Circuit Elements  Solution:  I = 1.75A  R = 16   V = ?

34. Circuits and Circuit Elements  Problem:  The wire in a house circuit is rated at 15.0 A and has a resistance of 0.15 . What is its power rating?

35. Circuits and Circuit Elements  Solution:  I = 15.0A  R = 0.15   P = ?

36. Circuits and Circuit Elements  Problem:  An electric motor operates a pump that irrigates a farmer’s crop by pumping 10,000 L of water a vertical distance of 8.0 m into a field each hour. The motor has an operating resistance of 22.0  and is connected across a 110V source. What current does it draw, and how efficient is the motor?

37. Circuits and Circuit Elements  Solution:  V = 110V  R = 22.0   I = ?

38. Circuits and Circuit Elements  Solution:  V = 110V  R = 22.0   I = 5.0A

39. Circuits and Circuit Elements  Homework  Pages 755-756  Problems:  17 (a, 24  b, 1.0A)  19 (a, 2.99  b, 4.0A)  26 (a, 1.7A b, 3.4V c, 5.1V d, 0.42A)