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How do LDRs work?

GW43125

Jul 2, 2014
13
Joined
Jul 2, 2014
Messages
13
Hello all,

A pretty basic question tonight, which the title pretty much explains already.

Anyway, does anybody know how an LDR can react to light and alter the resistance, and also why darker=more resistance?

I know this sounds dumb, but would anyone be able to explain it?

Thanks,
Jamie
 

Arouse1973

Adam
Dec 18, 2013
5,177
Joined
Dec 18, 2013
Messages
5,177
Hi Jamie

This is not a dumb question.

The LDR is actually made of a semiconductor material called Cadmium Sulphide and as light (photons) hit this material they knock out an electron from the valiant band of the atom and this electron is now ready to became part of the current through the LDR. The more light (Photons) that hit this material the greater the amount of electrons that are released and enter the conduction band to become the electrical current. So a higher current would indicate a lower resistor value (more electrons released) and the opposite happens in the dark a lower current occurs which indicates a larger resistor value (less electrons released).

Does this make sense?

Adam
 
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