paper 1

Cards (159)

  • current is the measure of the flow of electrons around the circuit, measured in amps by an ammeter
  • potential difference is the driving force of the flow of electrons and is measures in volts by a voltmeter
  • resistance is everything at opposes the flow of electrons and is measured in ohms
  • an alternating current changes direction
  • a direct current doesn't change dircetion
  • is a series circuit what is shared?
    potential difference
  • is a series circuit what is the same everywhere?

    current
  • a series circuit only has one loop
  • in a parallel circuit what is shared?
    current
  • in a parallel circuit what is the same in each component?
    potential difference
  • a parallel circuit has more than one loop
  • in a parallel circuit, the loops with a higher resistance have lower current
  • the more components in a parallel circuit the lower the resistance
  • in a series circuit the sum of the resistance in each component is the total resistance
  • how does the neutral wire complete the circuit?

    it carries the current away
  • what is the potential difference of the neutral wire?
    0v
  • what is the potential difference of the earth wire?
    0v
  • what does the earth wire do?
    stops the appliance becoming live if the live wire touches the casing as it provides an alternating pathway for current to flow
  • what colour is the earth wire?
    green and yellow
  • what colour is the neutral wire?
    blue
  • what colour is the live wire?
    brown
  • what is the potential difference of the live wire?
    230v
  • where does the live wire get the current from?
    mains supply
  • why is each wire made of copper?
    conduct electricity
  • why does a step up transformer increase the voltage?
    so current is kept low so less energy is lost as heat to the surroundings
  • what does a step up transformer increase?
    voltage to 400,000
  • what does a step down transformer do?
    decreases voltage to 230v for safety
  • when does electricity peak?
    in the late afternoon
  • what is a surge?
    a sudden increase in current
  • what can surges cause?
    fires, damage appliance, electrical shock
  • why is a high pressure dangerous?
    risk of explosion
  • what do fuses and circuit breakers do?
    break the circuit if the current is too high
  • what is the a fuse connected to?
    live wire
  • what does a fuse do if a high current passes through it?
    melts
  • why can fuses be costly?

    have to be replaced after each use
  • why are circuit breakers better than fuses?

    don't have to be replaced after each use
  • what can someone do to prevent electrical shock?
    -use earthing (an earth wire)
    -double insulating appliances (less likely to need an earth wire)
  • how do fossil fuels and nuclear power stations work?
    generate thermal energy with turns water into steam which turns a turbine then generates kinetic energy which can be converted into electrical energy and sent across the national grid
  • how are ammeters connected?
    in series
  • how are voltmeters connected?
    in parallel