LDR experiment
Here are some sample results of an experiment to investigate how the resistance of an LDR (measured using a digital mulitmeter) varies with the light intensity.
Method
A 60 W lamp was used as a light source, and the LDR's resistance was recorded as its distance r from the LDR was varied. The illuminance I was also recorded in lux (lx) using a luxmeter.
The laboratory flourescent tube lighting was left on during the experiment.
Results
The light intensity is proportional to the reciprocal of the square of the distance from the light source, and this was plotted against the LDR resistance in the graph below (click on graph for higher resolution image, also available as a PDF here):
The raw data are shown in the table below, and are also available as a tab delimited text file.
| r / m | I / lx | R / Ω |
|---|---|---|
| 0.1 | 7830 | 67.6 |
| 0.15 | 3060 | 95.6 |
| 0.2 | 1640 | 133.0 |
| 0.3 | 755 | 235 |
| 0.4 | 496 | 372 |
| 0.5 | 376 | 511 |
| 0.6 | 323 | 652 |
| 0.7 | 302 | 817 |
| 0.8 | 288 | 942 |
| 0.9 | 276 | 1076 |
| 1.0 | 257 | 1219 |
