The lab experiment is repeated with the same two glass plate

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 lambda_air = 610 nm. The separation between adjacent dark fringes is measured to be 0.490 mm. Calculate the diameter of the hair. (The length of the plates is 12.0 cm.)

Solution

1

the number of dark fringe: after that,

12 /0.049 = 244.9

Hence there 245 fringes,

2nt = (m + .5)*lambda

2(1)(t) = (245.5)(610 X 10^-9)

Hence

t = 74.88 X 10^-6 m

= 74.88 um