Figure 40-8 shows a laboratory setup for grating experiments. The diffraction grating has 5000 lines/cm and is 1.00 m from the slit, which is illuminated with sodium light. On either side of the slit, and parallel to the grating, is a meterstick. The eye, placed close to the grating, sees virtual images of the slit along the metersticks. Determine the wavelength of the light if each first-order image is 31.0 cm from the slit.