11 - plenary

 

11 - plenary

19 March 2012

11:10

·         Watch the video

·         Can you explain why the brightness of the LED can be varied? 

Your explanation should consider:

o the length of the graphite

o the resistance of the graphite

o the current in the circuit

Answer

·         A short length of graphite gives a low resistance

·         A low resistance allows a large current to flow

·         A large current makes the LED bright

OR

·         A long length of graphite gives a high resistance

·         A high resistance allows a small current to flow

·         A small current makes the LED dim