1. The problem statement, all variables and given/known data Used a solar cell and a ray box, altering the distance from the solar cell to the light source in 10cm increments. Did the usual high school experimental controls and repeats. Assuming that the voltage is proportional to the irradiance, I am meant to graph the results. 2. Relevant equations I1d12=I2d22 I = k / d^2 3. The attempt at a solution I graphed the results: http://imgur.com/a/Pc70V But as you can see, the inverse square graph isn't a straight line and I dont know why. Could it be my results or am I graphing it wrong?