1. What is DC Electricity. Chapter 2

2. Resistance The property of a material to inhibit the flow of current.

3. Resistor

4. Resistor Molded Carbon Composite

5. Resistor Wirewound Film Molded Carbon Composite

6. Wire wound

7. Film Surface Mount Technology SMT

8. Resistivity A L

9. Resistivity: Example A 1m long piece of gold has a cross sectional area of 0.1cm 2. The resistivity of gold at 20°C is 2.24 X 10 -8 ohm-meters.ρ ρ =2.24 X 10 -8 ohm-meters A = 0.1cm 2 L = 1m

10. Resistivity: Gold ρ =2.24 X 10 -8 ohm-meters A = 0.1cm 2 L = 1m R = ρL A R = (2.24 X 10 -8 Ώ-m)(1m) 0.00001m 2 R =0.00224 Ώ

11. Resistivity: Carbon ρ =50 X 10 -5 ohm-meters A = 0.1cm 2 L = 1m R = ρL A R = (50 X 10 -5 Ώ-m)(1m) 0.00001m 2 R =50 Ώ

12. Resistor Color Code 0 1 2 3 4 5 6 7 8 9

13. Tolerance 5% The measure of how good a component is. How close it is to the actual value. 10% 20% GoldSilverNo Band

14. Tolerance 100Ω 5%: 95-105Ω 10%: 90-110Ω 20%: 80-120Ω

15. } Digits 36 Multiplier 00000 Tolerance 5 % R =3600000 Ώ or 3.6M Ώ

16. } Digits 47 Multiplier Tolerance 20 % R =36 Ώ

17. Voltage Sources Voltage sources added in Series increase the Voltage and the Current stays the same. V = 1.5v I = 1A V = 4.5v I = 1A

18. Voltage Sources Voltage sources added in Parallel increase the Current and the Voltage stays the same. V = 1.5v I = 1A V = 1.5v I = 3A

19. Exampl e Exampl e Battery: V = 1.5v, I = 1A V=3v I= 3A V=3v I=1A

20. Ohm’s Law The Current(I) in a circuit is directly proportional to the Voltage(E,V) and inversely proportional to the Resistance(R). I = ERER

21. Ohm’s Law RI E Find: E E = I x R

22. Ohm’s Law RI E Find: R R = E/I

23. Ohm’s Law RI E Find: I I = E/R

24. Ohm’s Law Units RΩRΩ IAIA EvEv

25. RkΩRkΩ ImAImA E (v)

26. Ohm’s Law Units RMΩRMΩ IμAIμA E (v)

27. Ohm’s Law Example RΩRΩ IAIA EvEv R=2Ω, E=12v Find: I I = E/R =12v/2Ω I = 6A

28. Ohm’s Law Example RkΩRkΩ I mA EvEv E=120, I=60mA Find: R R = E/I =120v/60mA R = 2kΩ

29. Ohm’s Law Example RkΩRkΩ I mA EvEv R=10kΩ, I=12mA Find: E E = I x R =12mA x 10kΩ I = 120v

30. Wheel of Answers RΩRΩ IAIA EvEv R kΩ I mA EvEv