1. The problem statement, all variables and given/known data White light containing wavelengths from 396 nm to 756 nm falls on a grating with 7300 lines/cm. How wide is the first-order spectrum on a screen 2.15 m away? 2. Relevant equations y=m*L*wavelenth/(d) 3. The attempt at a solution using the equation I have found y1 to be 62.149 and y2 118.635. I took the difference of the two which gave me 56.486 cm, but that is wrong for some reason. Please help.