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Is there any component whose resistance increases with the increase in light?

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k_ishan

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I want a component or anything as light dependent resistor whose resistance increases with the increase in light following on it......
 
You could simply use an LDR (Light Dependent Resistor) with a transistor and one or two other components to work like this. Generally resistance of an LDR decreases with light, but with a little extra circuitry you can make it do what you want it to do.
Der Strom
 
If you're measuring voltage from it (like with an ADC on a microcontroller - via a voltage divider circuit) - you can simply place the LDR on the other side of the divider (that, or if using a microcontroller, you can invert the reading from the ADC in code). I know this isn't technically the same as what you want, but short of a more complex solution, its probably the simplest method...
 
I suspect that a liquid crystal might show that phenomenon of increased resistance -- at least in one orientation -- with light exposure. I did a quick search and could't find any examples of resistance being measured as a function of light exposure. The closest I could find was a reference showing that the alignment in a liquid crystal could be affected by absorbed light, but I didn't want to spend $$$ just to read the details. This free reference (https://www.electro-tech-online.com/custompdfs/2011/05/fulltext.pdf) reports that electrical resistance parallel or perpendicular to the molecular axis of a liquid crystal varies enormously (10E10 for this particular example). Thus, if you were measuring in the low-resistant perpendicular orientation and light caused some molecules to change, the resistance would increase.

I know that is just supposition and doesn't really answer your question, but maybe you will want to try the experiment. Remember, the light has to be absorbed by the liquid crystal, not just refracted by it.

John
 
I suspect that a liquid crystal might show that phenomenon of increased resistance -- at least in one orientation -- with light exposure. I did a quick search and could't find any examples of resistance being measured as a function of light exposure. The closest I could find was a reference showing that the alignment in a liquid crystal could be affected by absorbed light, but I didn't want to spend $$$ just to read the details. This free reference (https://www.electro-tech-online.com/custompdfs/2011/05/fulltext-1.pdf) reports that electrical resistance parallel or perpendicular to the molecular axis of a liquid crystal varies enormously (10E10 for this particular example). Thus, if you were measuring in the low-resistant perpendicular orientation and light caused some molecules to change, the resistance would increase.

I know that is just supposition and doesn't really answer your question, but maybe you will want to try the experiment. Remember, the light has to be absorbed by the liquid crystal, not just refracted by it.

John

Interesting idea - I'm not sure how well it would work with DC, though - I know that LCDs need to be driven with an AC signal, or something happens to them; not sure if this would be a problem...

I've never measured it, but what is the resistance of a solar cell (silicon or selenium - if that would make a difference?) in dark vs. sunlight?
 
Another candidate would be the organic conductors. You would have to test both the n-type and p-type, as I am not sure whether exciting an electron would add to or diminish conductivity. The underlying organic compounds should absorb a wide range of wavelengths.

John.
 
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