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Photoresistor
==============

.. image:: img/photoresistor.png
    :width: 200

A photoresistor or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photo conductivity. 

A photoresistor can be applied in light-sensitive detector circuits and light-activated and dark-activated switching circuits acting as a resistance semiconductor. In the dark, a photoresistor can have a resistance as high as several megaohms (MΩ), while in the light, a photoresistor can have a resistance as low as a few hundred ohms.

Here is the electronic symbol of photoresistor.

.. image:: img/photoresistor_symbol.png
    :width: 200

* `Photoresistor - Wikipedia <https://en.wikipedia.org/wiki/Photoresistor#:~:text=A%20photoresistor%20(also%20known%20as,on%20the%20component's%20sensitive%20surface>`_

**Example**

* :ref:`py_light_theremin` (For MicroPython User）
* :ref:`measure_light_arduino` (For C/C++(Arduino) User）
* :ref:`light_theremin_arduino` (For C/C++(Arduino) User）