resistance of a filament lamp

• Filament lamp

  A lamp that has a very fine wire filament that gets extremely hot when an electric current passes through it, causing it to glow and give out light
• Experiment with filament lamp

  1. Change potential difference

  2. Measure current
• Current through a filament lamp

  Not directly proportional to potential difference
• Filament lamp

  • Resistance increases at high temperature
  • Atoms in filament vibrate more, causing electrons in current to collide more with atoms, requiring more energy to push current through
• As potential difference increases

  Current no longer increases as much
• Filament lamp is not an ohmic conductor
• It is important to learn the shape of the current-potential difference graph for a filament lamp as it often comes up in exams
• You can find plenty of questions on the resistance of a filament lamp in the revision workbook