A red laser beam with a wavelength of 656 nm is used to determine the spacing of a diffraction grating. The first-order peak is observed 46.3 cm from the central maximum on a screen 0.8 m away.
a (9 pts) How many lines/mm is this diffraction grating?
b (9 pts) The same diffraction grating and setup is used to find the wavelength of a maximum on the screen. What is the wavelength of this laser beam?
d (6 pts) How many bright spots can you observe with this unknown laser beam?