P2 - Living For The Future Flashcards
What are the advantages of photocells?
- Robust
- Wireless & no fuel required
- No pollution
- Renewable energy source
What is a photocell?
A device that converts light into electricity.
What is the only disadvantage of photocells?
They do not produce electricity when it is dark or too cloudy.
What is a photocell made out of?
Two pieces of silicon that are joined together to make a p-n junction.
Why does n-type silicon have an impurity added?
To produce an excess of free electrons.
Why does p-type silicon have a different impurity added?
To produce an absence of free electrons.
What do photons do?
They cause free electrons to move - producing an electric current.
What does the output from a photocell depend on?
- Light intensity
- Exposed surface area
- Distance from light source
How can the current from a dynamo be increased?
- Stronger magnet
- Increased number of coil turns
- Rotate magnet faster
What is an oscilloscope used for?
To display the output from a dynamo.
What is efficiency?
A measure of how well a device transfers energy.
What is the National Grid?
A series of transformers and power lines that transport electricity from the power station to the consumer.
What is a transformer?
A device that can change the voltage and current of electricity.
What is ionisation?
The formation of ions.
Which form of radiation causes the most ionisation?
Alpha.
