P5: Mains Electricity Flashcards
What type of supply is mains electricity?
An alternating current supply
What is the frequency and potential difference of the domestic electricity supply?
50Hz and 230V
What colour are the 3 wires in mains electricity?
Live is brown, neutral is blue and earth is green and yellow
What is the function of the live wire?
Carries the alternating potential difference from the supply
What is the function of the neutral wire?
It completes the circuit
What is the function of the earth wire?
It is a safety wire which stops the appliance from becoming live. It only carries a current if there is a fault
What is the National Grid?
A system of cables and transformers linking power stations to consumers
What do step-up transformers do?
They increase the potential difference from the power station to transmission cables
What do step-down transformers do?
They decrease, to a much lower value, the potential difference for domestic use
What is the problem with increasing current to produce high power?
High current would mean lots of heat is generated due to the resistance in the wires, meaning lots of thermal energy is lost
When does electricity demand peak?
Late in the afternoon
What materials are the wires made out of and why?
Copper so they can conduct electricity
How are electric shocks from touching casing prevented?
The earth wire provides and alternative pathway for the current to flow away
What is the function of fuses and circuit breakers?
They break the circuit when current gets too high
Which wire it the fuse connected to?
Live
