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Problem 7: The 546.1 nm line in mercury is measured as a third order line with a distance of 0.350 m from the central part of the screen. The screen is 55.55 cm away. Calculate the number of lines per meter of this diffraction grating. na = d. sino : d =n7 / sing 2= 546.1 *10 n = 3 (3) (546. 1*10-9) = 8, 53 x 10-3 Sin (1. 10* 10-2 )