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LDR (Light Dependent Resistor)


Function of LDR

Function of an LDR (Light Dependent Resistor)

An LDR (Light Dependent Resistor) is an electronic component whose resistance changes according to the amount of light falling on it.

Function of an LDR

  • In bright light: the resistance of the LDR becomes low.
  • In darkness: the resistance of the LDR becomes high.

This property allows an LDR to act as a light sensor.

Common Applications

  • Automatic street lights (turn on at night, off during the day)
  • Light-sensitive alarms
  • Camera light meters
  • Solar garden lights
  • Brightness control in electronic devices

Working Principle

An LDR is made from a photoconductive material (commonly cadmium sulfide). When light strikes the material, more charge carriers are generated, allowing current to flow more easily and reducing resistance.

Summary

An LDR detects light intensity and converts changes in light into changes in electrical resistance.

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