I'm having trouble understanding the relationships between various variables at play in diffraction. Say you have diffraction with one slit, two slits, and a grating as shown below. So 1) The Amplitude of each peak is directly proportional to the intensity of the incoming waves. This makes sense. 2) The wavelength is directly proportional to the spacing between peaks. Is this because as the wavelength gets larger, less interference can occur so the spacing is greater? Versus if the wavelength is smaller, more interference can occur per area so the peak frequency is higher. 3) If you increase the distance between each slit, the spacing between each peak gets shorter. This I do not understand. I would think that if you increased the spacing in between each slit, that the spacing between peaks would be greater since there is more space in between the starting wavelets. 4) If you increase the distance between the starting screen and optical screen, then the spacing decreases. Is this because as you increase the distance you give the waves more time to interact and interfere. My text says it is because you are giving the interference pattern more distance over which to spread if you increase the distance L. But that would suggest to me that then the spacing would be greater if the waves are spreading out further 5) If you increase the number of slits, given the same "entering" intensity, then the amplitude of the each peak is greater and sharper. And the spacing in between each peak is greater with a greater number of slits. The relationship between # of slits and distance between each peak makes sense to me. If you have more slits, then for constructive interference to occur, more waves must interfere the right way to create that peak so theres a lower chance of it happening. Hence there are fewer peaks per area/amount of screen. Regarding peak intensity however, my text says, "Since a fixed amount of light should reach the screen, if the number of spots decreases, the intensity of each remaining spot should increase.". Conversely, if the number of slits increases, you should see lower intensity. But what we see actually happening is very different: More slits causes greater intensity here. Is it because the effect of having fewer fewer peaks (caused by having more slits) overpowers the effect of having more slits on the intensity of each spot? Also is "sharpness" a factor of brightness here? Thanks a lot guys. Spent all day trying to understand diffraction here. If there's any relationship i'm missing please tell me!