Light Dependent Resistor 7mm

This is a very small light sensor. A photocell (also called a photodetector, photo resistor, CdS or photoconductive cell) resistance depending on the amount of light it is exposed to. These little sensors make great ambient light triggers.A light dependent resistor works on the principle of photo conductivity. Photo conductivity is an optical phenomenon in which the materials conductivity is increased when light is absorbed by the material. When light falls i.e. when the photons fall on the device, the electrons in the valence band of the semiconductor material are excited to the conduction band. These photons in the incident light should have energy greater than the band gap of the semiconductor material to make the electrons jump from the valence band to the conduction band. Hence when light having enough energy strikes on the device, more and more electrons are excited to the conduction band which results in large number of charge carriers. The result of this process is more and more current starts flowing through the device when the circuit is closed and hence it is said that the resistance of the device has been decreased. This is the most common working principle of LDR.

Applications:

• Camera Exposure Control
• Auto Slide Focus
• Photocopy Machines
• Colorimetric Test Equipment
• Densitometer
• Electronic Scales
• Automatic Gain Control
• Automated Rear View Mirror
• Automatic Headlight Dimmer
• Night Light Control
• Oil Burner Flame Out
• Street Light Control
• Absence / Presence (beam breaker)
• Position Sensor

Package include:

• 1 x LDR 7mm Photoresistor Light Dependent Resistor