1. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 1

2. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 2 Electrical symbols

3. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 3 Basic circuit measurements

4. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 4 Meter symbols Digital Bar graph Analog

5. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 5 Current measurement

6. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 6

7. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 7 Current measurement

8. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 8 Current measurement Ammeter connection (series) +- !!Polarity a shown

9. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 9 Voltage measurement

10. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 10

11. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 11 Voltage measurement Voltmeter across the component (parallel) +ve to +ve -ve to -ve

12. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 12 Resistance measurement

13. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 13

14. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 14 Resistance measurement Disconnect R then make the measurement

15. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 15 Safety note

16. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 16 Physical effects of electrical current

17. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed., Floyd T. Elsarnagawy, mde207, 311 17 Ohm’s Law V-I-R

18. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 18 Voltage is Review of V, I, and R the amount of energy per charge available to move electrons from one point to another in a circuit. Current isthe rate of charge flow and is measured in amperes. Resistance is the opposition to current and is measured in ohms.

19. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 19 The most important fundamental law in electronics is Ohm’s law, which relates voltage, current, and resistance. Georg Simon Ohm (1787-1854) studied the relationship between voltage, current, and resistance and formulated the equation that bears his name. In terms of current, Ohm’s law states What is the current from a 12 V source if the resistance is 10  ? 1.2 A

20. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 20 Ohm’s law If you need to solve for voltage, Ohm’s law is: What is the voltage across a 680  resistor if the current is 26.5 mA? 18 V

21. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 21 Ohm’s law If you need to solve for resistance, Ohm’s law is: 120 V What is the (hot) resistance of the bulb? 138 

22. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 22 Graph of Current versus Voltage A student takes data for a resistor and fits the straight line shown to the data. What is the resistance and the conductance of the resistor? The slope represents the conductance. The reciprocal of the conductance is the resistance:

23. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 23 Graph of Current versus Voltage Notice that the plot of current versus voltage for a fixed resistor is a line with a positive slope. What is the resistance indicated by the graph? 2.7 k  What is its conductance? 0.37 mS

24. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 24 Graph of Current versus Resistance If resistance is varied for a constant voltage, the current - resistance curve plots a hyperbola. What is the curve for a 3 V source?

25. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 25 Application of Ohm’s law 26.8 mA

26. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 26 Linear Ohm’s law Troubleshooting Characterized by a straight-line relationship. A law stating that current is directly proportional to voltage and inversely proportional to current. A systematic process of isolating, identifying, and correcting a fault in a circuit or system. Selected Key Terms

27. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 27 1. Holding the voltage constant, and plotting the current against the resistance as resistance is varied will form a a. straight line with a positive slope b. straight line with a negative slope c. parabola d. hyperbola

28. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 28 2. When the current is plotted against the voltage for a fixed resistor, the plot is a a. straight line with a positive slope b. straight line with a negative slope c. parabola d. hyperbola

29. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 29 Quiz 3. For constant voltage in a circuit, doubling the resistance means a. doubling the current b. halving the current c. there is no change in the current d. depends on the amount of voltage

30. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 30 Quiz 5. If the current in a 330  resistor is 15 mA, the applied voltage is approximately a. 5.0 V b. 22 V c. 46 V d. 60 V

31. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 31 Quiz 7. The circuit with the largest current is a. (a) b. (b) c. (c) d. (d)

32. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 32 Quiz 8. The circuit with the smallest current is a. (a) b. (b) c. (c) d. (d)

33. Chapter 2-3 Principles of Electric Circuits, Conventional Flow, 9 th ed. Floyd T.Elsarnagawy, mde207, 311 33 Quiz Answers: 1. d 2. a 3. b 4. b 5. a 6. c 7. a 8. c 9. d 10. c