electricity-p5 Flashcards
what is current measured in
amperes
what is potential difference measured in
voltage
what is resistance measured in
ohms
what the equation for volt, amps and resistance
p.d = current x resistance
V=IR
what’s the equation of charge
charge= current x time
what’s the unit of charge
coloumbs, c
what’s the equation for power
power= current x potential difference
or
power = energy/time
what are step up transformers used for
to increase the p.d and decrease current
what’s the step down transformer used for
to decrease the potential difference and increase the current
what current reverses in direction
alternating current
what current moves in one direction
direct current
what is the direct current supplied by
the cells and batteries
what’s the alternating current supplied by
the mains supply
what voltage and hertz is the mains supply
230v and 50hz
what three wires are present in uk plugs
live wire, earth wire and neutral wire
what are the wires coated in
plastic
what colour is the earth wire
yellow and green
what colour is the live wire
brown
what colour is the neutral wire
blue
what the voltage of neutral wire
0v
what the voltage of live wire
230v
what the voltage of earth wire
0v
what is power measured in
watts, w
what’s energy measured in
joules,j
what’s time measure in
seconds,s
what’s the fuse connected to
the live wire
what happens if the current gets too hot
fuse wire heats up, melts and breaks
what the national grid
a network of cables and transformers
what are the pins in a plug made out of and why
brass so it doesn’t rust
what’s are the plugs made out of and why
stiff plastic because their good insulators
how do u get 1000 miliamps into 1 amp
divide by 1000
how do u get 1amp into 1000miliamps
times by 1000
what the equation for energy
energy = power x time
or
energy = current x time x p.d
what’s the equation for energy in kilowatt hours
energy(kwh) = power(kw) x time(h)
what’s efficiency’s equation
efficiency = useful output/ total input x 100
how do you get from 1000watt to 1kilowatt
divide by 1000
how do u get from 1 kilowatt to 1000 watt
times by 1000
what the equation for potential difference
p.d = energy/charge
or
p.d = current x resistance
