1. Interference and applications a/ Consider the two closely spaced spectral (yellow) lines of sodium (Na), 1= 589 nm and 2 = 589.6 nm. If light from a sodium lamp fully illuminates a diffraction grating with 1000 slits/cm, what is the angular separation of these two lines in the third-order (m=3) spectrum? b/ Suppose that when we pass red blue ( = 500 nm) through a slit of width a, the width of the spot (the distance between the first zeros on each side of the bright peak) is W = 1.5 cm on a screen that is L= 3m behind the slit. How wide is the slit?

1. Interference and applications a/ Consider the two closely spaced spectral (yellow) lines of sodium (Na), 1= 589 nm and 2 = 589.6 nm. If light from a sodium lamp fully illuminates a diffraction grating with 1000 slits/cm, what is the angular separation of these two lines in the third-order (m=3) spectrum? b/ Suppose that when we pass red blue ( = 500 nm) through a slit of width a, the width of the spot (the distance between the first zeros on each side of the bright peak) is W = 1.5 cm on a screen that is L= 3m behind the slit. How wide is the slit?