topic 2 (electricity) Flashcards
what is current
flow of electrons
what is potential difference
driving force that pushes current around the circuit
what is resistance
anything that slows down the flow of the current
series circuit:
- current is the same throughout the circuit
- pd is split across components
- resistance is all the resistance added together (R1+R2….)
parallel circuit:
- total current is split across branches
- pd is the same across each branch
- resistance = 1/R1+1/R2…..
AC & DC
Alternating current is a current that periodically reverses direction
Direct current is a current that always flows in the same direction
Mains electricity in the UK
230v and 50Hz
the national grid
the national grid is how we get electricity from power stations to our homes
power stations – step up transformer – pylons – step down transformer – homes
plug socket
Has three main wires :
- live wire
- the neutral wire
- the earth wire
live wire
the live wire is the brown wire - it carries high pd into and around the house , the live wire is always connected to the fuse plug
the neutral wire
the neutral wire is the blue wire , it is close to the earths potential and it has no current in it until it is connected to an electrical appliance
the earth wire
the earth wire is a safety wire there is normally no current in it
static electricity
when we have static electricity we have an object that is not normally charged become charged , which happens when two insulators rub against each other
here the move from one thing to another causing it to be charged
equations
E=pt (Energy trans[J], power[W] ,time[s])
E=Qv (Energy trans[J], charge flow[c] , pd [v])
p=vI (power[W], pd[v] , current[A])
p=I^R (power[W] , current [A] ,resistance [ohms])
v=IR (PD[v], current[A] , resistance[ohms])
Q=IT (charge flow [c], current[A] , time {s])
