Energy Flashcards
what is a short circuit?
Path of low resistance for current
what is a fuse?
electrical component with a low melting point, high resistance conductor
what is melting point?
tempreture at which substance melts
Advantages of circuits in parallel? (3)
- if one light fuses, rest will still work due to having its own parallel path
- other appliances still work if one is faulty
- current does not diminish if more lights switched on at same time.
dis advantage of circuit in parallel
parallel circuits can cause over loads on mains.
what is a circuit breaker?
electromagnetic switch that breaks circuit when current too high
how does the electromagnetic switch break?
high current makes magnetic field of electromagnet open switch
where is an electromagnetic switch found?
fusebox
what is a fuse made up of?
2 terminals and see through insulating materials
how does a fuse work?
short circuit overload (excess current) creates heat which melts fuse wire which stops current flowing in circuit
what are the 3 wires in a 3 pin plug?
brown(live), blue(nuetral), yellow/green(earth)
what is the function of the brown(live) wire?
carries alternating current
what is the function of the blue(nuetral) wire?
completes circuit (zero voltage)
what is the function of the yellow/green(earth) wire?
connected to appliance metal casing and goes into ground. if appliance charged by fault the earth wire discharges current as it has no resistance.
Safety precautions when wring a plug(4)
1. brown to L yellow/green to- E blue to N 2. fuse with correct value 3.no bare/loose wires 4. cable grip firm
what is electromagnetic induction?
copper coil moved through magnetic field which generates electricity(current)
name non renewable electricity powerstations (2)
coal burning and nuclear
name renewable electricity(3)
hydraulic, wind power and solar
how does coal burning powerstation work?
coal burn creates heat which boils water creating steam to turn turbine blades which is attached to generator shafts turning generator which creates electromagnetic induction
3 Adv of coal burning powerstion?
- coal is cheap
- coal is cheap to transport
- coal powerstation costs low
3 disadv of coal burning powerstation
- pollutes atmosphere
- non renewable
- cause acid rain and global warming
how does nuclear powerstation work?
nuclear fission of uranium and plutonium heats water etc…
3 adv of nucleur?
- cheap to maintain
- no greenhouse gasses
- less fuel for more energy
3 disadv of nucleur?
- expensive to build
- cancer risk
- hard to dispose radioactive waste
how does hydrolic work?
gravitational potential energy of water falling through canal spins turbine
3 adv of hydrolic?
- last long
- no greenhouse gasses
- large amounts of energy
3 disadv of hydrolic?
- expensive to build
- long time to build
- villages destroyed if dam walls burst
how does wind power work?
kinetic energy of wind to turn turbine
3 adv of wind power?
- renewable
- low operating costs
- can charge batteries when more wind to generate later
3 disadv of wind power?
- expensive to construct
- need constant wind supply
- noise pollution
how does solar work?
uses photo electric effect by using silicone layers. top has excess while bottom has storage electrons.
electrons are exited by light photons moving to bottom layer and inverter convert from DC to AC
3 adv of solar power?
- renewable
- low maintenance costs
- covering roof can cover annual costs for electricity
3 disadv of solar power?
- storage expensive
- lots of space needed
- not efficient
what is main electricity = to?
230V
what covert voltage higher and lower
step up and down transformers
what is power?
rate at which work done/ energy transfered
formula for cost of electric power
P(w.h /1000)= E(w)/t (hr)
formula for cost of electric power?
P(w.h /1000)= E(w)/t (hr)
how is electricity paid for
number of cents per unit( 1kWh = 1 unit)
