light dependent resistors

• Light Dependent Resistor (LDR)


  Also called a light dependent resistor, a type of resistor whose resistance changes depending on the amount of light shining on it
• LDR


  • High resistance in dark conditions
  • Low resistance in light conditions
• How LDRs work in circuits

  1. In light, LDR has low resistance so current can easily pass through

  2. In dark, LDR has high resistance so less current can pass through

  3. This changes the potential difference across other components in the circuit
• Uses of LDRs


  • Turning off mobile phone screen backlight when phone is held to ear
  • Turning on garden lamps in the dark
• LDRs are useful for detecting light