1. Current Electricity Chapter 22 the charges start to move

2. Electric Current Imagine a river, how do you measure its current? Is it the same as speed? Imagine a river, how do you measure its current? Is it the same as speed? Electric Current = Rate at which a charge moves through a cross section. Electric Current = Rate at which a charge moves through a cross section. I = Q/t I = Q/t = Coulombs/second = Coulombs/second = Amperes = Amperes

3. When you call someone in New York, how do they hear you? How does the signal get there? When you call someone in New York, how do they hear you? How does the signal get there? How fast do electrons travel? How fast do electrons travel? There would be quite a delay. There would be quite a delay. The actual speed is called Drift Velocity and is not the same as the speed of the signal. The actual speed is called Drift Velocity and is not the same as the speed of the signal. Electric Current

4. What if you place the Anode and Cathode from a battery in salt water? Which way does current flow? Current is defined as the flow rate of POSITIVE CHARGE

5. There are two basic types of current AC and DC AC and DC Alternating and Direct Current Alternating and Direct Current Electric Current eeeeee eeeeee

6. In a wire 10,000 electrons pass by every nanosecond. What is the current in the wire? Electric Current

7. Electrical Resistance = Ratio of potential difference to current within a material. Electrical Resistance = Ratio of potential difference to current within a material. Ohm’s Law Ohm’s Law V = IR volt = amp * ohm So, what does a resistor do? So, what does a resistor do? It controls current by turning electrical energy into other forms of energy. Electric Resistance

8. Determine the electrical resistance of a toaster. It is plugged into 115 V wall outlet and draws a current of 8.0 A. Electric Resistance

9. Electric Power Power = Rate of doing work = Watt (J/s) Power = Rate of doing work = Watt (J/s) P = J/C * C/s P = J/C * C/s P = Volt * Amp = V * I = Energy from the electric company is not measured in joules but instead is measured in kWh = kilowatt hours P = Volt * Amp = V * I = Energy from the electric company is not measured in joules but instead is measured in kWh = kilowatt hours Watt = Joules/sec so Joules = Watt sec Watt = Joules/sec so Joules = Watt sec

10. Electric Power A 40 W light bulb and a 75 W light bulb operate from 120 V. a) Which bulb has greater current? b) Which bulb has greater resistance?

11. Electric Power In one month, your family uses 600 kWh of electricity from the electric company. If electricity costs $0.20/kWh how much will you pay?

12. Electric Power If electricity costs $0.20/kWh, how much money will it be if you leave a 60W light bulb on for a whole day?