P5 Electricty In The Home
No description yet. This curated deck is ready for daily study.
Card preview (24)
What is a direct current
A current that only moves in one direction
What is an alternating cuurrent
A current that repeatedly reverses charge flow in one way then the opposite way is successive cycles
What is the mains frequency in the uk
50hz/cycles per second
What wires do main circuits have
A live wire and a neutral wire
In a graph what do AC and DC currents look like
AC currents move up and down over time DC is a straight line as the voltage stays the same the whole time
What is the potential difference between the neutral and earth wire
0 V
What is the potential difference between the live wire and the earth wire
230 V (Dangerous)
What does the earth wire do
Stops the metal case around a heater becoming live if it was live it could electrocute
How much electricity can a typical power station produce
Up to 25000 V
What are step up transformers
Transformers used to increase the alternating potential difference typically from 25000 V to 132000 V
What are step down transformers
Transformers used to supply electricity from the national grid to consumers They decrease the alternating potential difference to 230V
What colour are wires is a plug
The live wire is brown The earth wire is green and yellow The neutral wire is blue
What are plugs normally made of
Stiff plastic material due to them being good insulators
Why is the earth wire pin in a socket longer then the other two pins
So the earth wire connects first before the neutral and live wire adding another layer of protection
What does a fuse do
If too much current passes through the wire in the fuse it melts and cuts the live wire off
What is a short circuit
When the live wire touches the neutral wire causing a very big current that passes through the point in which both wires contact each other. It could cause a fire but the fuse melts and breaks switching off the current
What equation links power P with energy transferred E and time t
P = E/t
How do you calculate the energy transfer to a appliance each second
P = V(potential differance) x I(current)
How do you calculate what type of fuse an appliance needs
Using the power rating and the potential difference W = V x A W/V = A
What equation links power current and resistance
W = I^2 x R
When charge flows through a resistor,……
Energy is transferred to the resitor so the resistor becomes hotter
How do you calculate the energy transferred to a component
E = Q x V Energy Charge flow Potential difference transferred