P2a Flashcards
1
Q
How do photocells work?
A
- generate direct current like a battery
- made of silicon which is a semiconductor
- silicon atoms absorb light energy and some electons are knocked loose
- electrons flow round a circuit (electricity)
2
Q
What are some advantages of photocells?
A
- no moving parts so sturdy, low maintenance and long lasting
- no power cables needed or fuel
- solar power is renewable and doesn’t pollute the environment
3
Q
What are some disadvantages of photocells?
A
-no sunlight means no power
4
Q
How do curved mirrors concentrate energy from the sun?
A
-all radiation that lands on the curved mirror is focused right onto the object wanting to be heated
5
Q
What is passive solar heating?
A
-energy used directly from the sun
6
Q
Give some examples of passive solar heating.
A
- glass lets the Sun’s short wavelength through, but does not let the long wavelengths re-emitted by the heated objects in the room
- solar water heaters let heat in through glass and absorbs it with its black pipes
7
Q
What are wind wind turbines and how do they work?
A
- heat energy from the sun causes convection currents (wind)
- wind turbines convert the kinetic energy of the moving air into electricity/the wind turns the blades which turn the generator
8
Q
What are some benefits of wind farms?
A
- wind is free
- no polluting waste
- wind power is renewable
9
Q
What are some disadvantages of wind farms?
A
- 1500 turbines needed to replace one coal-fired power station
- noise pollution
- unaesthetically pleasing
- impossible to increases supply when there is a demand
- difficult to find suitable places to build wind turbines, requires being spaced out and very windy places
- expensive to set up
10
Q
What does direct current mean?
A
-current flows the same way round the circuit all the time
