P1 3 Electrical Energy Flashcards
What should electrical appliances do?
Waste as little energy as possible
What are electric appliances designed for?
A particular purpose
What is power?
The rate of energy transfer
If an appliance is more powerful, what happens to the rate at which it transfers energy?
It becomes faster
What is electrical power measured in?
Watts / kilowatts
What is a watt?
The rate of energy transfer of 1J/s.
How many watts are in a kilowatt?
1000
What is power equal to?
Energy/time
Power is in watts, energy is in joules and time is in seconds
How is the efficiency of power calculated?
Useful power out/ total power in (x100%)
What does the energy supplied to a device depend on?
How long it is used for and the power supplied to it.
What is a KWh?
A unit of energy; energy supplied to an 1KW appliance in an hour.
What does the total cost equal to?
The number of KWh used x cost per KWh
What do electrical appliances do?
They transfer electrical energy into useful energy very quickly.
What does cost effectiveness mean?
Getting the best value for money.
In order to compare the cost effectiveness of different appliances, what do you need to consider?
Account of costs to buy it, running costs and other costs such as environmental costs.
