It would be great if some could tell what exactly is the principle behind LDR.
Basically, LDR is an electronic component which is sensitive to light. As the intensity of light increases the electrons within LDR start getting more active. Therefore since there are more electrons the resistance decreases which the LDR had. Similarly if there is no light falling upon the LDR, The resistance will be quite high.
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We can say the principle behind the LDR is based on the Internal PhotoElectric effect. When the light is absorbed by the material the conductivity of the material increases i.e the electrons in the valency band are excited to the conduction band and so the resistance decreases.
The working principle of an LDR is photoconductivity, which is nothing but an optical phenomenon. When the light is absorbed by the material then the conductivity of the material enhances .An electronic component like LDR or light-dependent resistor is responsive to light. Once light rays drop on it, then immediately the resistance will be changed. The resistance values of an LDR may change over several orders of magnitude. The resistance value will be dropped when the light level increases.
Hello, I am Sanjeevni,
The answer is:
LDR works on the principle of photoconductivity which is an optical phenomenon.
When material absorbs light , the conductivity of material enhances.
When light falls on LDR , the photons in the incident light must have energy superior to bandgap of the material to make electrons jump from valence to conduction band.
Hence, when light having ample energy, more electrons are excited to the conduction band which grades in a large number of charge carriers. When the effect of this process and the flow of the current starts flowing more, the resistance of the device decreases.
Basically, LDR is an electronic component which is sensitive to light. As the intensity of light increases the electrons within LDR start getting more active. Therefore since there are more electrons the resistance decreases which the LDR had. Similarly if there is no light falling upon the LDR, The resistance will be quite high
When light falls on LDR Sensor, the photons in the light will make electrons jump from valence to the conduction band.
Hence, when light has ample energy, more electrons are excited to the conduction band which creates a large number of charge carriers. When the flow of the current increases, the resistance of the device decreases.
A Light Dependent Resistor is a type of resistor whose resistance changes with varying light levels. The resistance of an LDR decreases when exposed to light and increases in darkness. An LDR is typically made of a semiconductor material, such as cadmium sulfide (CdS) or cadmium selenide (CdSe). The semiconductor material is doped to create a light-sensitive region.The behavior of an LDR is based on the photoconductive effect. The semiconductor material in an LDR has a specific energy band gap. In darkness or low light conditions, the energy band gap between the valence band and the conduction band is relatively large, and very few electrons are excited to the conduction band.When light falls on the LDR, photons from the light source transfer energy to the semiconductor material. This energy can excite electrons in the valence band, allowing them to jump to the conduction band.LDRs are commonly used in various applications where light sensing or control is required. They can be found in light-sensitive switches, streetlights, cameras, security systems, and many other devices.
A Light Dependent Resistor (LDR) changes its resistance based on the amount of light it receives: high resistance in darkness and low resistance in light. This property makes it useful for light-sensing applications like automatic streetlights and camera exposure control.