A student sent white light through a diffraction grating with an unknown number of lines/m. First-order bright fringes were seen on either side of a light source, 1.00 m away from the diffraction grating, similar to the demonstration we did in the classroom. The distances to the left and right first-order pure violet bright fringes were measured to be 20.5 cm and 21.2 cm, respectively. 7. What was the diffraction grating 'rating' (in lines/m) in this experiment?

A student sent white light through a diffraction grating with an unknown number of lines/m. First-order bright fringes were seen on either side of a light source, 1.00 m away from the diffraction grating, similar to the demonstration we did in the classroom. The distances to the left and right first-order pure violet bright fringes were measured to be 20.5 cm and 21.2 cm, respectively. 7. What was the diffraction grating 'rating' (in lines/m) in this experiment?