ELECTRICITY

what is current

rate of flow of charge around circuit, A amps

• carried by electrons

when will current only flow

• if there is voltage across component

• positive to negative terminals

where must the ammeter and voltmeter be placed

AMMETER - SERIES

VOLTMETER - PARRALEL

mains supply is a.c, battery supply is d.c , wat dat mean

a.c - constantly changing direction

d.c - keeps flowing same direction

what does gradient of IV graph show

resistance behaves

what is a light emitting diode

• emit light when current flows through them

• they dont have filament that can burn out like old bulbs

what is light dependent reisstor

changes depending on how much light falls on it, bright light reistsance falls - burgulsr detetectprsm

what is thermistor

resiatnce changes based on temp, hot it deops - car engines

what is charge

rate of flow of electrical charge COLUMBS c

what colors are the wires

NETRAL BLUE

EARTH GREENYELLOW

LIVE BROWN

how does earth wire and fuse work;

• all appliances with metal cases must be earthed to reduce danger of electric shock

→ ‘earthing’ case must be attached to earth wire, because i can never be live and offers pathway for charge to go

• anything with double insulation doesnt need earth wire, plastic is insulator

• height in current melts fuse, cuts of live supply

→ impossible electric shock

what are circuit breakers

electrical safety device, protect is too much current flows

• when they detect hight in current they break by opening a switch, amd can easily be reset by flicking a switch

→ more convenient than fuses, have to be replaced once melted

→ more effienct and immidiate, dint have to melt

→ small current charged might not melt fuses, could be fatal

why do resistors get hot when electric current passes through them?

• there is an energy transfer which heats up resistor because electrons collide with ions in the lattice that makes up the resistor as they flow throw it

• the heating effect increases the resistance - less current will flow

adv; toasters have high reistance, when bread cooked it glows

disdv; can cause other components melt, circuit not work properly

what is electric power

rate at which an appliance transfers energy