Mains Electricity Flashcards
(22 cards)
What are the 3 wires in a plug?
- blue wire at the bottom on the left
- brown wire at bottom on the right
- yellow and green earth wire in the middle
why are wires made of copper?
copper is ductile and conducts
why are wires covered in flexible plastic?
because its an insulator
what are the pins made of and why?
pins made of brass because they’re strong & a good conductor
what happens to fuses who they get too hot?
they melt
what is the equation for power, energy and time?
power = energy (J)
(w) ———————
time (s)
what is the equation for power, current and voltage?
power = current (A)or (I)
(w) —————————–
voltage (V)
what are some faults with pin plugs?
- bare wires
- no cable grip
- cable grip not secured
- no fuse
- wires are wrong
- earth not connected
- wires too long/ not long enough
what are the 6 parts to a plug?
- yellow and green earth
- fuse
- brown live
- blue neutral
- cable grip
- cable
what are fuses?
safety devices
how can a fuse melt and break?
if a fault in an appliance ➡️ live wire or earth wire cross causes a large current to flow through fuse ➡️ fuse melts ➡️ breaks circuit
what is a circuit breaker?
breaks the circuit when current is too high
why is a circuit breaker better than a fuse?
- breaks circuit faster
- it can be reset
when are death wires used?
if an appliance has a metal case
if there is a … in the appliance, causing the … wire to touch the …, … takes … … route and surges down earth wire then … melts
if there is a FAULT in the appliance, causing the LIVE wire to touch the CASE, CURRENT takes LOW RESISTANCE route and surges down earth wire then FUSE melts
what does AC stand for and what is it? give an example
- alternating current
- current able to flow in both directions
- e.g. mains electricity
what does DC stand for and what is it?
- direct current
- current flows in 1D
- e.g. battery or a cell
what is the mains electricity and frequency in the UK?
- 230 v
- frequency ➡️ 50 Hz
what does a DC graph look like?
straight line across the top
what does an AC graph look like?
same size waves up and down
what is time period?
time to complete 1 wave
equation for frequency and period
frequency = 1 ➗ period
