Electrical Energy Flashcards
Why are electrical appliances useful?
They transfer electrical energy into whatever form of energy we need at the flick of a switch
Give some examples of common electrical appliances and the useful form of energy they produce.
- Lamps, to produce light
- Electric mixers, to produce kinetic energy
- Speakers, to produce sound energy
- Televisions, to produce light and sound energy
What should appliances be designed to do?
Waste as little energy as possible and fufill their particular purpose
How do many appliances tranfer energy and what might this mean?
Many appliances transfer energy by heating.
This may be useful, for example in a kettle, but often the energy is wasted
What is power?
The energy transformed or transfered per second.
It is measured in Watts (W)
Why is the joule not used by electrical companies when charging customers for energy?
Because it is not big enough (not a suitable resolution). Instead, kilowatt-hours are used
What is a kilowatt-hour?
The amount of energy transfered by a 1kW appliance when used for 1 hour
What does the electricity meter in a house record?
The number of kWh of energy used
What equation can be used to calculate the cost of electrical energy supplied (to a house)?
Total cost = Number of kWh X Cost per kWh
The cost per kWh is given on the electricity bill
What needs to be considered when thinking about/evaulating the cost effectiveness of an appliance?
- The inital cost of buying the appliance
- The cost of installing the appliance
- Running costs
- Maintenance costs
- Environmental costs
- The interest charged on a loan to buy the appliance
What might the environmental costs of an appliance include?
The removal or disposal costs of old equipment and environmental taxes
How might a household reduce their energy bills?
By installing newer, more efficient appliances (e.g. new fridge)
By installing materials desgined to reduce energy wastage (e.g. loft insulation)
What is payback time?
The time it takes for an appliance or installation to pay for itself in terms of energy savings
