Electrical appliances
What can you do for 1 unit (1 kWh) of electricity (cost: 15p in 2010)?
Appliance |
Time for one unit |
Appliance |
Time for one unit |
Mains radio |
30 hours |
Colour TV |
3 hours |
Blender |
Blend 300 litres |
Mains clock |
3 months |
Electric blanket |
Warm bed for a week |
Food mixer |
Mix 60 cakes |
Power drill |
4 hours |
Curlers |
Wave 22 heads |
Can opener |
Open 6000 cans |
Toaster |
Toast 70 slices |
Extractor fan |
24 hours |
CD player |
24 hours |
Hair drier |
3 hours |
Sewing machine |
Make 11 dresses |
Electric shaver |
2000 shaves |
Light bulb (100W) |
10 hours |
Battery charger |
One day |
Light bulb (100 W energy saving) |
4 days |
Vacuum cleaner |
2 hours |
Iron |
2 hours |
Radiant heater |
1.25 hours |
Stereo system |
8-10 hours |
Carving knife |
220 joints of meat |
Microwave |
3 kg joint |
Black and white TV |
7 hours |
Sandwich toaster |
38 sandwiches |
How much energy do appliances use?
Appliance |
Energy used |
Electric cooker |
1 kWh per person per day |
Freezer |
35 kWh per week per m3 |
Fridge |
1 kWh per day |
Unlagged hot water tank |
160 kWh per week |
Lagged hot water tank |
80 kWh per week |
Microwave |
0.4 kWh for each kg cooked |
Shower (7 kW) |
3 to 4 kWh per week |
Storage heater (2 kW) |
45-75 kWh per week |
Electric blanket |
3 kWh per week |
Tumble drier |
Dry 4kg for 2.5 kWh |
Knife sharpener |
15000 knives for 1 kWh |
Slow cooker |
1 kWh in 8 hours |
It is interesting to compare the power of various types of television. Televisions come in different sizes so I have picked a 40” screen size.
Traditional CRT TV |
Power on 192 W |
Standby 1.92 W |
LCD TV |
Power on 200 W |
Standby ranges form 1.00 W to a staggering 40 W |
Plasma TV |
Power on 250 W |
Standby ranges from 1.3 W to 12 W |
For the LCD screen with the standby of 40W you would use 105 kWh if you simply left it on standby for a year!
A VERSION IN WORD IS AVAILABLE ON THE SCHOOLPHYSICS USB