Graphs

• Ohmic conductor : current directly proportional to potential difference

  -straight line (at constant temperature)
• Filament lamp : current increases = temperature increases

  -> harder for current to flow

  graph becomes less steep
• Diode : current only flows in one direction

  resistance very high in other direction = no current can flow
• Ohmic conductor :

  
• Filament lamp :

  
• Diode :