1. Electric Current

2. The rate at which electrical charges flow through a wire or conductor is called electric current.The rate at which electrical charges flow through a wire or conductor is called electric current. Electrical current = charge passing through a given area / time I = Δ q/ Δt SI Unit = C/s = Amperes (A)

3. Electric Current Sample Problem The current in a light bulb is 0.835 A. How long does it take for a total charge of 1.67 C to pass a point in the wire? I = Δq/Δt Δt = Δq/I = 1.67 C / 0.835 A = 2.00 s Δq = 1.67 C I = 0.835 A

4. Electric Current Charges flow from high voltage to low voltage. –A voltage difference is the push that causes charges to move. –Voltage difference is measured in volts (V). –For charges to flow, the wire must always be connected in a closed path, or circuit.

5. Electric field travels at the speed of light, but the charges do not!!! Drift Velocity: The net velocity of a charge moving in an e - field. Electric Current

6. 2 Types: 1. Direct current (DC) - Electrical charges move only in one direction. - Batteries always generates a direct current (why?……fixed voltage difference). Types of Current

7. Direct Current

8. Types of Currents (cont.) 2. Alternating current (AC) - Electrical charges are constantly changing directions. - Commonly used in homes and businesses throughout the world. Why? More efficient for long-distance electrical charge transmission.

9. Alternating Current

10. Sources of electrical current A dry cell battery produces a voltage difference –zinc container –carbon suspension rod –causing current to flow between them. Example: AA battery

11. Dry Cell Battery

12. A wet cell battery contains two connected plates made of different metals in a conducting solution. –Example: Car battery Sources of electrical current (Cont.)

13. Generators -Convert mechanical energy to electrical energy. -Can produce both direct and alternating current. Sources of electrical current (Cont.)

14. Wall sockets have a voltage difference across the two holes of an electrical outlet. –generator at a power plant provides this voltage difference. Sources of electrical current (Cont.)