Diodes and LEDs

• What is a light emitting diode (LED)?

  A diode that emits light when current flows
• How does the current through a resistor behave with potential difference?

  It is directly proportional as long as temperature is constant
• Why is the current through a filament lamp not directly proportional to potential difference?

  Because the filament gets hot, increasing resistance
• What are the key features of a diode?

  • Current flows in one direction only
  • High resistance in the reverse direction
  • Symbol includes an arrow indicating current direction
• What happens when the current flows in the forward direction through a diode?

  The diode allows the current to pass through
• What occurs when the cell in a diode circuit is reversed?

  The diode does not allow current to pass through
• What does the current potential difference graph for a diode show?

  No current flows in the reverse direction
• Why are diodes useful in circuits?

  They control the flow of current effectively
• Where can you commonly find LEDs?

  • In camera flashes
  • In LED light bulbs
  • In LED televisions
• How does an LED differ from a normal diode?

  An LED emits light when current flows through it
• Why are LEDs considered energy efficient?

  They provide light with low energy consumption
• What is the significance of the arrows in the LED symbol?

  They indicate the emission of light