1 / 17

Chapter 17

Chapter 17. Current and Resistance Electric current Drift speed Current and voltage measurement Ohm’s law Resistivity Superconductivity Electric energy and power. Electric Current. What is an electric current? How do I calculate current? What are the SI units?

meg
Download Presentation

Chapter 17

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 17 Current and Resistance • Electric current • Drift speed • Current and voltage measurement • Ohm’s law • Resistivity • Superconductivity • Electric energy and power

  2. Electric Current • What is an electric current? • How do I calculate current? • What are the SI units? • What is the direction of current in a circuit? • What is conventional current?

  3. Current and Drift Speed • Current defined in terms of charge carrier and drift speed • Isolated conductor • Conductor with electric field • Drift speed and circuits

  4. Example • The battery pack of a pocket calculator has a voltage of 3.0 V and delivers a current of 0.17 mA. In one hour of operation, • How much charge flows in the circuit? • How much energy does the battery deliver to the calculator circuit?

  5. Meters in a Circuit • What is an ammeter? • How do I connect it in a circuit? • What is a voltmeter? • How do I connect it in a circuit?

  6. Resistance • What is a resistor? • What is the relationship between voltage and current in a circuit? • What is electrical resistance? • What the SI units of resistance? • What is Ohm’s law?

  7. Georg Simon Ohm • 1787 – 1854 • Formulated the concept of resistance • Discovered the proportionality between current and voltages

  8. Ohm’s Law • Statement of ohm’s law • What is an Ohmic device? • What is non-Ohmic device? • Examples

  9. Example • A filament in a light bulb is resistor in the form of a thin wire. The wire becomes hot enough to emit light because of the current in it. A flashlight uses two 1.5 V batteries to provide a current of 0.40 A in the filament. Determine the resistance of the glowing filament.

  10. Resistance & Resistivity • What is resistivity? • Resistivity of metals? • See table 17.1 • Resistance and Temperature

  11. Example • The heating element in an electric stove contains a wire of 1.1m and cross-sectional area 3.1x10-6 m2 through which electric charge flows. The wire becomes hot in response to the flowing charge. The resistivity of the material is 6.8x10-3 °C-1 at 320 °C. Determine the resistance of the heater wire at an operating temperature of 420 °C.

  12. Superconductors • What are superconductors? • Why superconductors?

  13. Energy Transfer in the Circuit • What is grounding? • Energy considerations

  14. Electrical Energy and Power • What is power? • How do I calculate it? • What are the SI units? • What is kilowatt-hour? • Conversion factor

  15. Example • In the flashlight the current is 0.40A and the voltage is 3.0 V. Find • The power delivered to the bulb • The electrical energy dissipated in the bulb in 5.5 minutes of operation.

  16. Electrical Activity in the Heart Normal

  17. Implanted Cardioverter Defibrillator (ICD) • Devices that can monitor, record and logically process heart signals • Then supply different corrective signals to hearts that are not beating correctly

More Related