Topic 2 - Electricity

• A power source for an electric circuit could be what?

  cell, battery
• What does a switch symbol look like?

  
• What is current?


  the flow of electrons around a circuit
• What does a battery look like

  
• what is current measured in?


  amperes (amps)
• What does a filament lamp look like?

  
• What is potential difference?

  force driving the flow of electrons around a circuit
• In 'conventional current', we say that the electrons flow from

  Positive terminal ➔ negative terminal
• What is resistance?


  everything that resists or opposes the flow of electrons in a circuit
• What is potential difference measured in?

  Volts
• what is resistance measure in?


  Ohms (Ω)
• What formula relates voltage, current, and resistance?

  V = IR

  
• What happens to resistance when the temperature is increased in wires and resistors?

  Resistance increases
• What is the current / voltage graph for a filament lamp?

  
• What is the current / voltage graph for a fixed resistor?

  
• What is a diode?

  A component that only allows current to flow in one direction

  
• What is the current / voltage graph for a diode.

  
• What is charge?


  measure of the total current that flowed within a period of time
• What is the formula for charge?

  charge = current x time

  
• What is charge measured in?

  Coulombs, C
• What is the symbol of a cell?

  
• What is the symbol for a fuse?

  
• What does an emitting light diode do?

  Only allow current to flow in one direction

  Emit light when current flows through it
• What is the symbol for a light dependent resistor?

  
• What is the symbol for a thermistor?

  
• What is the symbol for a variable resistor?

  
• What is the symbol for a fixed resistor?

  
• A resistor whose resistance decreases when temperature increases is a

  thermistor
• What is a series circuit?

  A circuit that has only one path for the elecric current to flow.
• What is a parallel circuit?

  circuit that has more than one path for electric current to flow
• In a series circuit how is the current shared?

  The same everywhere in the circuit
• What is Ohms law?

  V=IR
• What does a step up transformer do?

  increases voltage and decreases current
• What does a step down transformer do?

  decreases voltage and increases current
• What is the national grid?

  A giant system of cables and transformers that covers the UK and connects power stations to consumers
• How does the national grid work?

  Electricity is transported from a power station to a step-up transformer, to power lines, to a step-down transformer, to consumers.
• What is alternating current?


  A flow of electric charge that regularly reverses its direction.
• What is direct current?

  Current that flows in only one direction
• What is an oscilloscope


  Display how voltage changes with time
• In the UK, the mains supply is alternating current and has a frequency of __ Hz and a voltage of ____V

  50, 230