LDR (Light Dependent Resistor) and How to Measure It – Light Dependent Resistor or abbreviated as LDR is a type of resistor whose resistance value or resistance value depends on the intensity of light it receives. The LDR Resistance value will decrease when the light is bright and the Resistance value will be high if it is dark. In other words, the function of LDR (Light Dependent Resistor) is to conduct an electric current if it receives a certain amount of light intensity (Light Condition) and inhibits electric current in dark conditions.
The ups and downs of the Barrier value will be proportional to the amount of light it receives. In general, the LDR Resistance Value will reach 200 Kilo Ohm (kΩ) in dark conditions and decrease to 500 Ohm (Ω) in Bright Light Conditions.
LDR (Light Dependent Resistor) which is a Light Sensitive Electronics Component is often used or applied in Electronic Circuits as sensors in Street Lighting Lights, Bedroom Lights, Anti-Maling Circuits, Shutter Cameras, Alarms and so on.
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LDR Shapes and Symbols
How to Measure LDR (Light Dependent Resistor) with Multimeter
The measuring instrument used to measure the resistance value of the LDR is a Multimeter with ohm measurement function (Ω). In order for LDR measurements to be accurate, we need to make 2 lighting conditions, namely measurements in dark conditions and light conditions. Thus we can find out whether the LDR Component can still function properly or not.
Measuring LDR in Bright Conditions
- Set the position of the Multimeter selector scale at ohm position
- Connect the Red Probe and the Multimeter Black Probe on both legs of the LDR (no polarity)
- Give bright light to the LDR
- Read the resistance value on the Multimeter Display. The LDR Resistance value in bright conditions will range from about 500 Ohm.
Measuring LDR in Dark Conditions
- Set the position of the Multimeter selector scale at ohm position
- Connect the Red Probe and the Multimeter Black Probe on both legs of the LDR (no polarity)
- Close the surface of the LDR or make sure the LDR does not get light
- Read the resistance value on the Multimeter Display. The resistance value of LDR in dark conditions will range around 200 KOhm.
- Measurement results will change depending on the level of light intensity received by the LDR itself.
- The unit of light or illumination is lux.
Other designations for LDR (Light Dependent Resistor) are Photo Resistor, Photo Conduction or Photocell.
