Please help. :(

Structures on a bird feather act like a diffraction grating having 9000 lines per centimeter. What is the angle of the first-order maximum for 477 nm light shone through a feather? angle:I' E,I,L 41,7; l,,, Enter numeric value from the slits is projected onto a screen that is 2.90 m away. 1 500-nm wavelength is incident upon two narrow slits that are separated by 0.500 mm. An interference pattern What is the separation distance Dbl on the screen of the rst bright fringe from the central bright fringe? What is the separation distance Dd; on the screen of the second dark fringe from the central bright fringe