P2 Flashcards
define current
the flow of electrical charge
give an equation that links current, charge and time, with units for each
charge flow(coulombs, C)= current(amps, A) * time(seconds, S)
what is the equation that links potential difference current and resistance
potential difference (v)= current (A) * resistance (ohms)
what is an ohmic conductor
a conductor which follows ohms law
what happens to the resistance of a thermistor as it gets hot
the resistance drops
is potential difference shared between components in a series circuit
yes
how does the current through each component vary in a series circuit
there will be less current flowing through them the more components you have
is current shared between the branches of a parallel circuit
yes
is mains electricity alternating current
yes
what is the potential difference and the frequency of the UK mains supply
frequency is 50 HZ
PD is 230 V
what colour is the earth wire
green and yellow
what wire is blue
neutral
what wire is brown and dangerous to touch
live
why is the live wire dangerous
it has about 230 v in it
describe the energy transfers that occur for a battery-powered fan
electrical energy
what is the power rating of an appliance
it tells you how much power the appliance uses, given in watts or kilowatts
3 equations used to calculate power
potential difference * current = power
power = energy transferred/time
power=current squared * resistance
what is the national grid
a giant web of wires that covers the whole of Britain spreading the electricity to homes
why is electricity transferred by the national grid at a high PD but low current
so it is more efficient
what are the functions of step up and step down transformers
they increase and decrease the potential difference
