What are the characteristics of LDR?

Characteristic of the LDR sensor LDR sensor are very sensitive to light. The stronger the light, the lower the resistance. With the increase of illumination intensity, the resistance value of the ldr photoresistor decreases rapidly, and it can be reduced to less than 1K.

What is light dependent resistor PDF?

4.6 LIGHT DEPENDENT RESISTOR A Light Dependent Resistor (LDR) or a photo resistor is a device whose resistivity is a function of the incident electromagnetic radiation. Hence, they are light sensitive devices. They are made up of semiconductor materials having high resistance.

What is the working principle of LDR?

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. When the light falls on the LDR, then the electrons in the valence band of the material are eager to the conduction band.

How are light dependent resistors used?

This makes the electrons to jump from the valence band to conduction. These devices depend on the light, when light falls on the LDR then the resistance decreases, and increases in the dark. When a LDR is kept in the dark place, its resistance is high and, when the LDR is kept in the light its resistance will decrease.

Who invented light dependent resistor?

The idea of Photoresistor developed when photoconductivity in Selenium was discovered by Willoughby Smith in 1873. Many variants of the photoconductive devices were then made.

Where are light dependent resistors used?

LDRs (light-dependent resistors) are used to detect light levels, for example, in automatic security lights. Their resistance decreases as the light intensity increases: in the dark and at low light levels, the resistance of an LDR is high and little current can flow through it.

What is the meaning of light dependent resistor?

Light Dependant Resistor. A light dependant resistor also know as a LDR, photoresistor, photoconductor or photocell, is a resistor whose resistance increases or decreases depending on the amount of light intensity. LDRs (Light Dependant Resistors) are a very useful tool in a light/dark circuits.

What is the function of LDR in circuit?

LDRs (Light Dependant Resistors) are a very useful tool in a light/dark circuits. A LDRs can have a variety of resistance and functions. For example it can be used to turn on a light when the LDR is in darkness or to turn o˜ a light when the LDR is in light.

How many pins are connected to an LDR?

One of the pins of the LDR is connected to the ground while the other is connected to one of the 5 analogue in pins. Depending on the function of the LDR it may need another resistor connected to it.