1 / 11

Voltage and Current

Voltage and Current. Whenever positive and negative charges are separated, Voltage is the energy per unit charge created by the separation. Where v = the voltage in volts w = the energy in joules q = the charge in coulombs. Voltage and Current (continued).

morrison
Download Presentation

Voltage and Current

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. Voltage and Current • Whenever positive and negative charges are separated, • Voltage is the energy per unit charge created by the separation. Where v = the voltage in volts w = the energy in joules q = the charge in coulombs ECE 201 Circuit Theory I

  2. Voltage and Current (continued) • The rate of charge flow is electric current Where i = the current in amperes q = the charge in coulombs t = the time in seconds ECE 201 Circuit Theory I

  3. Power and Energy • Power is the time rate of expending or absorbing energy. Where p = the power in watts w = the energy in joules t = the time in seconds 1 Watt = 1 Joule/second ECE 201 Circuit Theory I

  4. Power Associated with the flow of charge • Using the definitions of Voltage and Current Where p = the power in Watts v = the voltage in volts i = the current in amperes ECE 201 Circuit Theory I

  5. The Basic Ideal Circuit Element • The ideal basic circuit element • has only two terminals • is described mathematically in terms of current and/or voltage • Cannot be subdivided into other elements ECE 201 Circuit Theory I

  6. Passive Sign Convention If the power is positive (p>0), power is being delivered to the circuit inside the box. If the power is negative (p<0), power is being extracted from the circuit inside the box. ECE 201 Circuit Theory I

  7. Circuit Theory • What is an electric circuit? • A mathematical model that approximates the behavior of an actual electrical system. • Example: Automobile Headlights • Here the headlights are OFF and draw no current from the battery because the switch is open. ECE 201 Circuit Theory I

  8. Automobile Headlights (continued) • Turn the headlights ON by closing the switch. The headlights are ON. They draw a current of 4.138 Amperes from the battery. ECE 201 Circuit Theory I

  9. Jump Starting ExampleProblem #1.15 • The current is measured to be – 40 Amperes. Which car has the dead battery? ECE 201 Circuit Theory I

  10. The current is flowing into the + terminal of the battery in car A. p = vi = (12V)(-40A) = -480W Since the power is negative, the battery in car A is generating power. Car B has the dead battery ECE 201 Circuit Theory I

  11. Problem # 1.15 part (b) • If this connection is maintained for 1.5 minutes, how much energy is transferred to the dead battery? ECE 201 Circuit Theory I

More Related