1. 19.1 Electrical power  In some electrical appliances, electricity can be easily converted into other forms of energy. heat energy light energy kinetic energy Energy change in electrical appliances sound energy

2. 19.1 Electrical power Heating effect of electric current  An electric current flows through the wire.  Temperature Heating effect of electric current Electrical energy is dissipated in the wire.

3. 19.1 Electrical power Electrical power and power rating  Different electrical appliances convert electrical energy at different rates.  SI unit of electrical power: watt (W)  1 W = 1 J s  1  Electric power or rate at which electrical energy is converted into other forms of energy =

4. 19.1 Electrical power Power rating label of an electric iron  When this iron is connected to a 220 V supply, 1000 J of electrical energy are converted every second.

5. 19.1 Electrical power Power ratings of some common electrical appliances Electrical appliancePower rating (W) Calculator0.001 Television100 Fan240 Microwave oven800 Electrical iron1000 Hair dryer1200 Electric kettle2000

6. 19.1 Electrical power  Energy transferred to the appliance, E = QV What is the electrical power of an electrical appliance if V and I is known?  Substituting it into, we have P = VI

7. 19.1 Electrical power Power dissipated in a resistor  Voltage across a resistor, V = IR  Current through a resistor,  Substituting them into P = VI, we have and or

8. 19.1 Electrical power That’s the end of Section 19.1 Check Point Key Ideas Previous Page Section 19.2 Exit