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: I was wondering if you can help me, : I need to find the equation for the intensity of light in Joules, preferably in terms of the distance from the light source. : I need this for a physics cousework. : I know theses equations: I=Io/4(pi)r sqaured : I=nhf (although I am not sure what all the letters mean, if you could help I would be grateful) : I = nE (same as brackets above) : The reason I need to know this is I am doing a study on the resistance of an LDR in relation to the distane from the light source. : As light intensity is proportional to 1/the distance squared, I thought my graph would look like a 1/x squared curve, but instead I got a straigt line. Trying to expleain this I found the equation for the resistance of a thermistor (which is basically the same semiconductor principle as an LDR) : the equation is I (current) is proportional to e(2.718..)to the power of -E (the curvy one i think is energy if you know could you say)/kt : so it can be said the R (resistance) is proportional to 1/ the left side of the above equation : I need to replace kT with something that symbolizes the light energy in joules : Do you have any suggestions? : If you do, or have answers to any of the questions above, or know someone who might could you please write back : : Thank you very much : : Laurence Fahrni

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