Current Electricity

1. Current Electricity Page 314: 10.9

2. Electric Current: • RECALL: In static electricity, an electric charge stays in one area. • In current electricity an electric charge moves through conductors along a path • Its electrons that move NOT protons! • A cell, battery or a direct current from a wall plug provide the energy to push electrons

3. Current electricity is generated and used as a source of energy in homes and industry. • Current electricity is a flow of electrons, usually through a CONDUCTOR. • In all dry CELLS, the flow of ELECTRONS moves from negative to POSITIVE. • The electrons flow in ONE direction ONLY!

4. Electron movement e-

5. Electric Circuit • Electric circuit: a closed controlled path for charges to move. • All circuits contain at least 3 of the following parts: • Source of Electrical Energy: a power source such as a battery or a wall outlet • Electrical Load: something that converts electrical energy into another form. Loads are the reason the circuit exists in the first place. Ex. Light bulb or a toaster. • Connectors: A conducting wire that allow the charges to move from the power source to the load. • Electric Circuit Control device: these are switches that can stop the flow of charges in the circuit. Ex. A light switch or a timer on a microwave ***NOT all circuits contain switches

6. Moving Electrons can be changed to many other desired forms… • Kinetic (movement), light, sound, heat

7. Current • Current is the amount of electrical charge MOVINGfrom one place to another. (The amount of electrons moving) • Current is represented by the symbol, I and is measured in amperes (amps or A) with an AMMETER.

8. Example: There is more current running through a toaster (13.6 A) than a wristwatch (0.00013A).

9. Measured in Amperes… • SI unit for current is ampere, (A) • Symbol for ampere is I • Slightly less than 1A runs through a 100W lamp connected to a 120V circuit • Measured using an ammeter • Equivalent to the current in a river

10. Moving Electrons… Current= rate of electron movement

11. What makes up Current? • Current is the charge moving past a point in a conducting wire every second. Therefore the number of coulombs/second = current. • WHAT IS CHARGE???? • CHARGE is measured in COULOMBS • 1 coulomb of charge = the charge on 6.25X10 18 electrons • Time is measured in seconds

12. FORMULA WHERE: I is the current measured in Amperes (A) Q is the charge measured in coulombs (C) t is the time measured in seconds (s)

13. Example 1: 1. What is the current through a circuit with 3 coulombs of charge in 10sec? G: Q= 3C, t=10s R: I =? A: I= Q/t = 3C/10s S: I= 0.3 A S: Therfore, there is 0.3A of current flowing through the circuit

14. Example 2: 2. What is the charge within a circuit that has 6 A of current over 3 seconds? G: I= 6A, t=3s R: Q =? A: I= Q/t Q= It S: Q= 18 C S: Therfore, there are 18 coulombs of charge flowing through the circuit

15. Example 3 3. How much time will it take for 12C of charge to pass through a circuit with 5 A of current? G: Q= 12C, I= 5A R: t= ? A: I = Q/t t = Q/I t = 12C/5A S: t = 2.4 s S: Therfore, it will take 2.4s

16. Voltage • Voltage is the force that moves electric charges in a circuit. Makes the currents flow. Measured in volts (V) by a VOLTMETER. • Ex. Batteries can be stronger or weaker depending on their voltage. A 9V battery provides more force than a 6V battery

17. Resistance • Resistance is the ability that tries to stop or slow down the electric charges in a circuit. Measured in OHMS by an Ohmmeter . = ohms • Example: a light bulb in a circuit creates resistance as the electrons slow down and create so much heat the light bulb glows

18. Electric Shock • Feel it at .001 A (tingling at 0.002) • “let go threshold” (0.016A convulse); can’t breathe • Usually fatal at 0.05A (heart stops, fibrillates) • 0.833A- amount needed to light a 100-W lamp

19. The body closes the circuit… • Muscles automatically contract until flow stops

20. Can cause severe burns at exit points…

22. What to do if the victim… • loses consciousness; • is thrown by the shock; • touched a voltage source of more than 600 V; • has burn marks on skin at points of contact with current. Generally, the only outward sign of internal burns is electrical marks at the contact points. Internal damage may thus be much more serious than the external injuries suggest. Call an ambulance

23. Don’t touch the victim. You might get a shock, too! • Disengage the victim from the electric current by • cutting the power at the source or • using a nonconductive object to free the victim from the energy source without touching him or her directly.

25. A raccoon suffered an 11,000 voltelectric shock when it scampered up a pylon in Cyprus but escaped with burns.

26. F1: BMW mechanic receives electric shock at Jerez

27. Electroshock fishing… • Survey Streams /content without killing

28. Electroshock therapy...

29. Questions: • 1. What is current? • What 2 things make up current and how do they affect the flow of electrons? • How is electricity converted to other forms of energy? • What 4 types of energy are electricity converted to? • Explain what to do when someone is receiving an electric shock? • What are some uses of electric shock?