1. Natural Sciences and Technology Grade 6
Term 3: Energy and Change
Mains Electricity (ppt 3)

2. Topic 4 Mains Electricity Cost of electricity
Natural Sciences and Technology - Grade 6

3. Natural Sciences and Technology - Grade 6
Electricity is costly [expensive]. It is a struggle to balance budgets.
Natural Sciences and Technology - Grade 6

4. Electricity requires infrastructure
Infrastructures, which are very expensive, are needed to bring electricity to us.
In South Africa it has been planned to install 4,700 kilometres of new power liners from 2008 until 2018.
The cost of power lines is approximately R1,5 million per kilometre.
Natural Sciences and Technology - Grade 6

5. Electricity requires infrastructure
Natural Sciences and Technology - Grade 6

6. Electricity requires infrastructure
The Kusile power station in Mpumalanga will cost R142 billion to build. [It will be the fourth-largest coal-fired power station in the world].
It also cost billions to keep every infrastructure as well as the equipment in good and proper working order.
It is therefore required that everyone who uses electricity must pay for it.
Natural Sciences and Technology - Grade 6

7. Some electrical appliances require more electricity than others
Every electrical appliance has a wattage rating. [kettle requires more than W; a radio require 14 W].
A watt is a measure of how much energy something uses.
Heaters, geysers and stoves have high wattages and it uses a lot of electricity.
Pollution increases as we use more electricity because more coal must be burnt.
Energy-saving bulbs use less electricity.
Natural Sciences and Technology - Grade 6

8. Natural Sciences and Technology - Grade 6
Ways to save energy
Use low-wattage appliances [e.g.]
Solar water heating systems.
Natural Sciences and Technology - Grade 6

9. Natural Sciences and Technology - Grade 6
Ways to save energy
2. Use energy-saving light bulbs.
Natural Sciences and Technology - Grade 6

10. Natural Sciences and Technology - Grade 6
Ways to save energy
3. Switch off appliances that are not in use.
Natural Sciences and Technology - Grade 6

11. Watt output of different devices
APPLIANCE
POWER in W [watt]
POWER IN kW [kilowatt] V
[volt] mV
[milliampere]
CD player
35 W
0.035 kW
Electric kettle
2000 W
2 kW
Frying pan
1200 W
1.2 kW
Cell phone charger
36 W
240 V
150 mA
Electric blanket
200 W
0.2 kW`
Computer
115 W
230 V
500 mA
Natural Sciences and Technology - Grade 6

12. Watt output of different devices
APPLIANCE
POWER in W [watt]
POWER in kW [kilowatt]
television set
60 W
0.06 kW
automatic washing machine
500 W
0.5 kW
energy saving bulb
15 W
0.015 kW
hair blow dryer
1000 W
1 kW
electric iron
1400 W
1.4 kW
Natural Sciences and Technology - Grade 6