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Unit 12 Electric Current

Unit 12 Electric Current. Flow of Charge and Electric Circuits. Water Flow Model. High Potential Energy Water. Water Pipe. Height. Water Doing Work. Pump Doing Work. Low Potential Energy Water. Water Flow vs. Electric Current. High Potential Energy Water. Water Pipe. Height.

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Unit 12 Electric Current

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  1. Unit 12Electric Current

  2. Flow of Charge and Electric Circuits

  3. Water Flow Model High Potential Energy Water Water Pipe Height Water Doing Work Pump Doing Work Low Potential Energy Water

  4. Water Flow vs. Electric Current High Potential Energy Water Water Pipe Height Water Doing Work Pump Doing Work Low Potential Energy Water

  5. Electric Current Model High Voltage Electric Circuits Voltage Electric Current Doing Work Battery Doing Work Low Voltage

  6. Water / Electric Current Model

  7. Electric Current Model High Voltage Electric Circuits Voltage Electric Current Doing Work Battery Doing Work Low Voltage

  8. Electric Current Model High Voltage Electric Circuits Electric Current Doing Work Battery Doing Work Voltage Low Voltage

  9. Light Bulb Structure

  10. Electric Circuit Symbols Wire Resistor Battery Voltage

  11. Electric Circuits Wire Battery Resistor

  12. Electric Circuits

  13. Ohm’s Law

  14. Electric Current Current (I) Voltage (V) Resistance (R)

  15. Electric Current I (amperes , A) V (volts, V) R (ohms, Ω)

  16. Ohm’s Law V I R

  17. Ohm’s Law V: Voltage (V) I : Current (A) R: Resistance (Ω)

  18. Voltmeter – Measuring Voltage V V

  19. Ammeter – Measuring Current A A

  20. Multimeter – Measuring All V: Voltage (V) I : Current (A) R: Resistance (Ω)

  21. Digital Multimeter – Measuring All V: Voltage (V) I : Current (A) R: Resistance (Ω)

  22. Digital Multimeter – Measuring All

  23. Digital Multimeter – Measuring All Voltage / Resistance Current Ground

  24. Digital Multimeter – Measuring All

  25. Digital Multimeter – Measuring All Resistance DC Voltage AC Voltage DC Current AC Current Transistor

  26. Ohm’s Law A V (V) I (A) R (Ω) V

  27. Ohm’s Law

  28. Ohm’s Law voltage = constant x current V = R x I V: Voltage (V) I : Current (A) R: Constant or Resistance (Ω)

  29. Ohm’s Law V V R = orV = I R or I = I R V: Voltage (V) I : Current (A) R: Resistance (Ω)

  30. Ohm’s Law Example • What is the current through a 4-ohm resistor connected to a 12-V power supply?

  31. Ohm’s Law Example • What is the current through a 4-ohm resistor connected to a 12-V power supply? I = V / R I = 12 V / 4 Ω = 3 A

  32. Ohm’s Law Example • A 5-ohm resistor has a 8-A current in it. What is the voltage across the resistor?

  33. Ohm’s Law Example • A 5-ohm resistor has a 8-A current in it. What is the voltage across the resistor? V = I R V = 8 A x 5 Ω = 40 V

  34. Ohm’s Law Example • What is the resistance of a device that uses 2.5 A of current when connected to a 15-volt power source?

  35. Ohm’s Law Example • What is the resistance of a device that uses 2.5 A of current when connected to a 15-volt power source? R = V / I R = 15 V / 2.5 A = 6 Ω

  36. Ohm’s Law Exercises • What is the current through a 6-KΩ resistor connected to a 9-V power supply? • What is the resistance of a device that uses 0.5 mA of current when connected to a 5-volt power source? • A 2.5-MΩ resistor has a 0.02-mA current in it. What is the voltage across the resistor?

  37. Resistors

  38. Resistors • A resistor is a two-terminal electronic component which implements electrical resistance • Resistors are used to control the amount of current flowing in a circuit • Resistor are usually measured by the units of Ω, kΩ, and MΩ

  39. Resistors

  40. Resistors on PCB

  41. Resistor Color Coding

  42. Surface Mount Resistors

  43. SMT Resistors on PCB

  44. Resistance andResistivity

  45. Resistance • Electric current in a circuit is decided by voltage (V) and resistance (R): I = V / R • What are the factors to determine the resistance?

  46. Resistance & Length • Which one has larger resistance?

  47. Resistance & Length • Which one has larger resistance?

  48. Resistance & Length • Which one has larger resistance? R ~ L

  49. Resistance & Area • Which one has larger resistance?

  50. Resistance & Area • Which one has larger resistance?

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