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The lab experiment is repeated with the same two glass plates but with a different human hair. The sodium vapor lamp is replaced by a monochromatic light source that produces light of wavelength
The separation between adjacent dark fringes is measured to be 0.485 mm. Calculate the diameter of the hair. (The length of the plates is 12.0 cm.)
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The lab experiment is repeated with the same two glass plates but with a different human hair. The sodium vapor lamp is replaced by a monochromatic light source that produces light of wavelength
The separation between adjacent dark fringes is measured to be 0.450 mm. Calculate the diameter of the hair. (The length of the plates is 12.0 cm.)
answer
The first dark spot is at the zero location where the glass plates touch. To find the number of dark fringes after that, divide 12 cm by .45 mm
12/.045 = 266.7
Since you can't have a portion of a dark fringe, that means there are 266 additional dark fringes and therefore 267 bright fringes. The end with the hair must be a bright fringe to account for the .7
That will be the 266th bright fringe
Apply 2nt = (m + .5)wavelength
2(1)(t) = (267.5)(640 X 10^-9)
t = 8.56 X 10^-5 m (That is 85.6 um)