1. Energy Transfer & Transformation

2. Power Power (P) – the rate of conversion of electrical energy (scalar)
Units – Watts (W)
The electric power in watts represents the rate at which energy is converted from  electrical energy to some other form of energy, e.g., mechanical energy, heat,  light, etc.

3. A very good example of a home appliance with a high wattage is a hair dryer.
It needs only two parts to generate the hot air that dries your hair:
* a heating element
* a motor-driven fan
Hair dryers use the heating element ( a simple wire with some resistance ) to transform electric energy into heat.

5. Electrical Energy
Electrical Energy (W) – the energy made available by the flow of electrical charges through a conductor (scalar)
Units – Joules (J)

7. The Cost of Electrical Energy
Electricity meters measure the number of units of electricity used in a home or other building. Units (kilowatt-hours) are used instead of joules because a joule is a very small unit of energy. You wouldn’t buy potatoes by the milligram!

8. So what exactly is a kilowatt hour?
A kilowatt hour (kWh) is a measure of how much energy you’re using.
It doesn’t mean the number of kilowatts you’re using per hour. It is simply a unit of measurement that equals the amount of energy you would use if you kept a 1,000 watt appliance running for an hour:
So if you switched on a 100 watt light bulb, it would take 10 hours to rack up 1 kWh of energy.
Or a 2,000 watt appliance would use 1 kWh in just half an hour.
While a 50 watt item could stay on for 20 hours before it used 1 kWh.

11. Energy Transmission