Photosensitive resistor is a special kind of resistor, referred to as photo resistor, also known as light pipe. Its resistance is directly related to the intensity of light. As the light intensity increases, the resistance decreases; when the light intensity decreases, the resistance increases.
When exposed to light, electrons that are originally in a stable state in the resistor are excited to become free electrons. So the stronger the light, the more free electrons are produced and the smaller the resistance.
Dark resistance: When the resistance is in a state where there is no light at all (room temperature), the resistance value at this time is called dark resistance (when the resistance value is stable, for example, 1 kM ohm), and the current corresponding to the dark resistance is dark current. .
Bright resistance: When the resistance is in a state of sufficient light (room temperature), the resistance value at this time is called a bright resistance (when the resistance value is stable, for example, 1 ohm), and the current corresponding to the bright resistance is a bright current.
Photocurrent = bright current - dark current
We certainly hope that the sensitivity of the photoresistor is higher, that is, the photocurrent is larger.
1. The internal photoelectric effect is independent of the electrode (the photodiode is related), that is, the DC power supply can be used.
2. Sensitivity is related to the semiconductor material and the wavelength of the incident light
Photoresistors are commonly used in security monitoring, street lighting, alarms, stair lights, nightlights, and when the light is dark, the street light is on.
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