light-dependent resistors

• (LDR)

  Also called a light dependent resistor
• LDR

  • Has high resistance in dark conditions
  • Has low resistance in light conditions
• How LDRs work in circuits

  1. LDR has low resistance in light

  2. Low resistance in LDR means high current and low potential difference across LDR

  3. High potential difference across lamp

  4. Lamp lights up

  5. LDR has high resistance in dark

  6. High resistance in LDR means low current and high potential difference across LDR

  7. Low potential difference across lamp

  8. Lamp dims
• Devices using LDRs

  • Mobile phone screen backlight
  • Garden lamps
• LDRs can be used to detect light and control circuits accordingly