Electricity

• What is the definition of charge?

  A measure of the total current that flowed within a certain period of time
• What is the calculation for working out the charge?

  Charge = Current x Time

  Q = I x T
• What is charge measured in?

  Coulombs
• Where does most of our electricity come from?

  Power stations
• What are step up transformers used for?

  Increasing the voltage
• What are step down transformers used for?


  decreasing the voltage and increasing the current
• In series circuits the potential difference of the battery is shared across all the components
• What does AC stand for?

  Alternating Current
• What does DC stand for?

  Direct current
• All mains supply is alternating current
• What are oscilloscopes used for?

  Measuring voltage over time.

  Showing graphs of potential difference verses time.
• Energy = Power x Time
• Energy = Voltage x Current x Time
• Energy = Charge x Voltage
• Power = Current x Voltage
• Power = Current x Current x Resistance
• Current is the same everywhere in a series circuit
• Components with a greater resistance will have a greater share of the voltage
• What is the definition of current?

  A measure of the flow of electrons around the circuit
• What is the definition of potential difference?

  The force driving the flow of electrons
• What is the definition of resistance?

  Everything that opposes or resists the flow of electrons
• Which way does conventional current flow?

  From the positive terminal to the negative terminal
• This is the symbol for a battery

  
• This is the symbol for a filament lamp

  
• This is the symbol for a thermistor

  
• This is the graph for a filament bulb

  
• What do fuses do?

  They break the circuit if the current gets to high
• What happens to the fuse when there is a surge?

  It gets really hot and melts/breaks
• What does it mean if a live wire touches the casing?

  That if someone touches the casing it could give them a big electric shock
• How does double insulation stop you from getting electric shocks?

  The double insulation is made of plastic which can’t conduct electricity
• What is static electricity?

  Bulid up of electric charge on insulating materials.
• If the potential difference between a charged object and an earthed object is big enough, the electrons can jump and cause a spark.
• What happens when two insulating objects rub together?

  Some electrons from one object rub onto the other object so one object is positive and one is negative
• What does a negatively charged particle look like with the electric field aswell?

  Electric field lines radiate inward to the negatively charged particle.

  
• What is the frequency of the mains electricity supply in the UK?


  50 Hertz