cables and plugs. Flashcards
what is the voltage of the mains electricity on the UK?
230v.
how many times does the mains electricity change direction?
50 times a second.
if the mains electricity changes direction 50 times a second what does that mean the frequency is?
50 Hz.
the mains supply uses what type of cable?
3 core cable.
what does each cable carry that is different?
electrical potential.
what is the name of the wire that is: brown: and what is its voltage potential?
live wire.
230 v potential.
what is the name of the wire that is: blue : and what is its voltage potential?
neutral wire.
at or close to 0v earth potential.
what is the name of the wire that has: green and yellow strips: and what is its voltage potential?
earth wire.
o v potential.
during operation: what does the potential difference cause to flow and where?
current.
live and neutral wire.
during operation: the live wire carries what from where?
alternating potential from supply
during operation: what does the neutral wire do?
completes the circuit.
during operation: what conditions allows only for the current to flow in the earth wire?
a fault connecting it to a non-zero potential.
what can the earth wire be classed as and what does it do?
safety wire.
stops the exterior of an appliance becoming live.
what circuit is used in house wiring?
parallel.
why is that certain circuit used for house wiring?
otherwise everything would have to be on.
what does the live wire carry?
electric current to an appliance.
what does the neutral wire do?
completes the circuit.
how does the neutral wire do its job?
forms a path for current to flow back to the mains.
what is the potential difference between the neutral and earth wire?
usually close to 0V.
how is the earth wire usually connected to the circuit?
metal case of an appliance.
what does the earth wire provide?
very low resistance path for a current in the event of the appliance becoming live.
what are cables usually made out of?
copper.
why are cables usually made out of copper?
good conductor and bends easily.
what is a good electrical insulator and prevents people getting an electrical shock if they touch the cable?
plastic.
which wires are stored in a 2 core cable?
neutral and live.
what are 2 core cables used in and why?
appliances with a plastic case as they don’t need to be earthed. double insulated.
what is the symbol for a 2 core cable?
a box with a smaller one inside.
what can be changed about a cable and where would we see it, technical terms and an example?
different thicknesses, different appliances.
cable for the cooker is thicker than the one for the lights.
how does a fuse work: stage: 1.
energy is dissipated.
how does a fuse work: stage: 2.
fuse wire gets hot.
how does a fuse work: stage: 3.
if the current is larger than the current rating for the fuse it melts.
how does a fuse work: stage: 4.
this disconnects the power supply to the appliance.
how does a fuse work: stage: 5.
protects the appliance from taking a current that might damage it or cause the wiring to overheat.
what happens if the live wire touches the metal case and what is large enough to do?
a large current flows to earth.
melt the fuse which cuts the power supply to the appliance.
