# LDR: Why is conductance proportional to log(intensity)?

1. May 9, 2009

### Beam me down

I am doing a experimental report on various solid state devices and have come unstuck on my work with LDRs. I have data relating conductance of a CdS photo-resistor to intensity of (white) light. The problem is that I am completely unsure as to why there is a log relationship, as has been suggested to me. I understand why there is an increase in conductivity (hence decrease in resistance), as there are more electrons in the conduction band.

Any hints you can provide would be greatly appreciated,.

Cheers,
Matthew

Last edited: May 9, 2009