LDR PROJECT ( light dependent resistance)

Hello sir,
Today i.have finished LDR PROJECT which is light dependent resistance. I am confused about results.
No.1 up to 10th reading when the room light was on the results was 1.02 thousand.
No.2 from 11th reading when the room light was off thr results was 30,36,40 etc…

Hey @mohammedarshad6894
The highest reading from the LDR provided with the starter kit is 1.02 thousand only. Whether you put the device under the sun or in the room with the lights ON, it will still show the same reading since they are more than 1.02 thousand.

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Hi @mohammedarshad6894,
The readings that you get are the analog readings of the sensor. If the room is brightly illuminated, the readings will be higher. If the light is less, the readings will come down. This is how it works. Hope you are satisfied with the answer. The least value it can read is 0, I suppose, the highest value is 1024.
I do hope that this helps you @mohammedarshad6894.:smiley:

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Thank you.@kashika1104

Thank you very much @sskzm5808

My pleasure! @mohammedarshad6894 and don’t forget to mark the better one of these two as an answer.

@mohammedarshad6894, Thanks a Lot!

The intensity of light falls on the surface of LDR is inversly proportional to the resistance of LDR. The resistance is very high in dark and low in light. So, when lights falls on sensor ,readings will be higher and in darkness, reading will be low. LDR can provide highest reading upto 1.02 thousand.

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Hey @mohammedarshad6894 as we know the highest reading of LDR from the starter kit is 1.02 thousand and thus even if you keep the lights on or provide extra amount of light to the LDR say artificial lights or sun or with rooms light on,it will only show you the same reading of 1.02 thousand as it is the maximum value of the kit and as you turn off the lights after the 10th reading the values will Start decreasing as for a LDR the resistance increases with decrease in light and thus the reading also decreases.

I hope this helps you.

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LDR is giving reading in terms of voltage. such as V=(5XR1)/(R1+R2) where R1 is fixed resistor we connected-10K and R2 is LDR resistor.
Suppose if bright light is there, then Resistor R2 is less so voltage is more and when light is less, Resistance R2 is more and voltage is less. Hope it will clear your doubt @mohammedarshad6894

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Hi @mohammedarshad6894
As you can see from the circuit connection, this is a simple electrical connection with 3 components, 1 voltage source (say Vcc), 2 resistances (1 fixed resistance Rf, 1 variable resistance Rv). What you are getting as output (Vo) is basically the voltage across the fixed resistor and that is proportional to circuit current I (= Vcc/(Rf + Rv)). Now since, Rf is fixed, I will depend upon Rv. When the environment is bright, LDR resistance is low (own property). So, I will be high, causing the output to be high (Vo= I*Rf). Similarly, when brightness is low, Rv is high, I is low & Vo is low.
Now, coming to the part of maximum value, for some certain brightness, Rv is zero, but if the environment is brighter, that can’t cause the output to be higher than a certain value. That’s why 1024 is the higher limit. Hope it helps.