[填空题]
When yellow sodium ligkf0 ai/6zmw3k ( umhg:q9y: 3suj avi:ko9v2 bht, $\lambda\;=\;$ falls on a diffraction grating, its first-order peak on a screen 60.0 cm away falls 3.32 cm from the central peak. Another source produces a line 3.71 cm from the central peak. What is the wavelength of the new source? How many $lines/cm$ are on the grating?
nm
$ lines/cm$
