# Plan Monitoring System

In the hardware configuration of the plant monitoring system through LDR, we have to insert a 10k ohm resistor.
I know that the A0 pin operates from 0 to 1 V, that is the reason resistor is used along with LDR. But is the range of 10k ohm specifically chosen ? Can’t we use any other resistor of different ohmic value?
Because I tried to configure it using a low ohmic resistor than 10k and in that case I was getting the max value, that is 1024… Is that due to the wrong resistor?

Please elaborate! As I have used a low ohmic resistor will the LDR be damaged or what. Why I am getting a constant value by using a different resistor

The range of 10K ohm is specifically taken, but little +/- will also work .Yes @vishalvats2000,because of using wrong resistor you are getting max value that is 1024. By using appropriate ohmic resistance, no harm will be caused to the LDR. Basically we are using resistance so that more current does not flow through the LDR. So, by using low ohmic resistor our LDR will gradually get damage as it cannot withstand high current flowing through it. But in case if your LDR has some internal resistance, in that case taking low ohmic resistor will work and high ohmic resistance will show max value that is,1024.

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Yes sir. It’s now working fine

@vishalvats2000

Basically we use resistor to avoid large current from flowing through our LDR and avoid damage,in my case i recieved an LDR with internal resistance which is different from standard. so i was getting 1.02 thousand value always. To solve this i used a 330 Ohm resistor in place of 10k resistor and rest of the circuit connection remains same.