My lecturer discussed bragg's law a few weeks ago and described how the angle theta changes as the wavelength is doubled. I cant seem to duplicate his result. I know that the bragg condition for a maxima would reduce to : dsinθ=mλ when the wavelength is doubled. In his example he knew that maxima were observed at 20.5 and 44.5 degrees but he gave no other values. How would I go about predicting the angles at which the maximas are now observed ?