P7.2.1 - Energy, power, and paying for electricity Flashcards
1
Q
In electrical devices, energy is transferred when charge moves:
A
- from a chemical store of a battery, or
- from a chemical or nuclear store of the fuel in a power station used to produce mains electricity
2
Q
What is power rating?
A
The rate of transfer of energy by an appliance
3
Q
For domestic appliances what is the unit for energy?
A
kilo-watt hour
4
Q
What is the equation used for calculating energy for domestic appliances?
A
power(kW) = (electrical) work done(kWh)/time(h)
5
Q
Suggest and explain one reason for buying a hairdryer with a high power rating.
A
It transfers electrical energy into heat/kinetic energy faster so the hair dries quicker
6
Q
Suggest and explain whether using higher-power devices is cheaper, more expensive, or costs the same as using lower-power devices.
A
- Higher power devices transfer electrical energy faster to other forms.
- In the same time, they will use more energy.
- So, they will cost more to run.
- However, if the higher power of the device makes it
more efficient at doing its job - It won’t need to be on for as long a period of time…
- So may actually end of using less energy and so costing less money to use.
