Investigation of a light dependant resistor.

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Investigation of a light dependant resistor

Light dependant resistors or LDRs are resistors which alter their resistivity according to a particular light level. I am going to find out how these work and use them in a context so I can use them to locate a light source. To do this I must firstly find out how light effects the LDRs and then use this data to try and create something in order to detect a light source and locate it.

Results

Distance light is away from LDR

Voltage reading (supply-12v)

5cm

11.5

10cm

10.9

15cm

8.7

20cm

6.4

25cm

3.7

30cm

1.9

As you can see from these results as the light intensity increases, the resistance decreases. I need to find the range of light levels the LDR can detect and distinguish how sensitive it actually is. The maximum resistance it is possible to get from the LDR is 550k?. This is when there is maximum light shining on the LDR. The minimum resistance that is possible is 0.90k?. This is when the LDR is submitted