1. More electricity stuff

2. Direct current (DC)
This is current that moves in one direction only. It’s useful when electric current does not have to travel too far… i.e. in the circuits you build.
Batteries are examples of direct current.

3. Alternating Current (AC)
This is current that continuously changes direction within wires. This is more convenient for sending electric current over long distances.
Wall sockets and power lines have AC.

4. Explain the role of a fuse or breaker in a circuit.

5. Power
This is the amount of work an electrical device can perform in a certain period of time.
In other words, it considers how much energy a device can transform over time.

6. Watt?

7. Watt?

8. Watt?

9. Watts
A watt is a
Joule
sec

10. Power Power is calculated with the following formula:
P is power (in Watts)
V is voltage (in volts)
I is current (in Amps)

11. How do we calculate Power?
Suppose you have a circuit with a potential difference of 12 volts and a current of 8 amps passing through an electric device.
Calculate the resistance
Calculate the power

12. Summary
All you need to calculate power is voltage (v) and intensity (I).
So if you can do Ohm’s law, you can calculate power as well!

13. Energy
Energy is the ability of something to do work. It is measured in _______________.
Remember, the formula for determining Power is: P = V x I

14. Calculating how much energy an appliance uses
To figure out how much energy a device uses, you need to know how much power is involved, and the amount of time involved.

15. Calculating how much energy an appliance uses
To figure out how much energy a device uses, you need to know how much power is involved, and the amount of time involved.

16. TIP: Always show your units, even in calculations!!!
Example: A 1000 W microwave operates for minutes. How much energy does it use?

17. A 200 W stereo used 2.88 million joules of energy over a certain amount of time. How long was it on for?

18. Another unit for Energy
Joules represent very small amounts of energy. If we want to know how much energy is used for larger appliances for longer amounts of time, it helps to have a bigger unit: