2. Our power points consist of two components, with an optional third Active Neutral Earth (optional)

3.  This is a typical diagram for wiring of an appliance.  Note Earth is there for safety, and not used in all appliances.

4.  The active end is connected to the active supply and puts out an oscillating +340v to - 340v or 240v RMS  The neutral end is connected to the neutral terminal of the supply box. This is then connected to the Earth, with a rod into the ground.  So the electricity flows out of the active and into the neutral.

5.  Split into groups of 4  Find out about 1. What kind of Voltage can kill someone? 2. What effect does current have on the human body? In respect to exposure time and/or amount of current. 3. How would you treat someone who has been shocked? 4. Name a piece of medical equipment that uses or measures electrical activity and discuss how it works. 5. Discuss with class.

6.  Out of your power point, we run 240v AC  The power is supplied at 10 Amperes  What is the power at a power point?

7.  Being AC, this means the direction of the flow current changes.

8.  Power, energy and the relationship with voltage and current.  Power is how fast energy is being converted to another form. i.e. Electricity to heat (toaster) or Electricity to sound (speaker).  Power = Energy / Time  Energy = Power x Time

9.  As we know electricity is made up of two main parts current and voltage.  We get our Power from current and Voltage so:  Power = Voltage x Current, (P = VI)  Energy = Voltage x Current x time (E = VIt) 

10.  Damaged extension cords or appliances can ‘leak’ electricity.  This leak can result in a short circuit, damaging the appliance or even you.  To stop this from happening, older buildings used fuses.  A fuse will melt if it has too much current and create an open circuit.

11.  Newer buildings and large supply boxes use circuit breakers.  If they detect a high load of current, they will open, creating an open circuit.

12.  Most appliances have a power rating listed somewhere on them. Usually given in Watts.  A Microwave might use 12000 Watts, a Toaster 1800 Watts.  If the AC Supply is 240v and Toaster uses 1800 Watts  1. What is the current the toaster draws?  2. What is the resistance of the toaster in use?

13.  Harry is charging his phone at home. (assume 240v rms)  It draws a current of 1.5 Amps  How much power does it draw?  If left charging for four hours, how much energy has he used in; i) kWh? ii) Joules?

14.  Storage cells are special types of cells that current can be reversed through them.  This reverses the process that produces the charge, meaning you can recharge the battery  List some common types.