(Equation 17.6) Write the equation for the path-length difference at a bright fringe (constructive interference). Define all variables. What are the SI units of each variable

  d sin tea = m λ

Explanation:

When we have a two-slit system, the optical path difference determines whether the intensity reaching an observation screen is maximum or zero.

To find this difference in optical path, we assume that the screen is much farther than the gap is, we draw a perpendicular from ray 1 to the second ray

       OP = d sin θ

now to have constructive interference and see a bright line this leg must be an integer number of wavelengths, ose

            d sin tea = m λ

where

d             is the distance between the two slits

θ     complexion the angle sea the point hold it between the two slits

λ    the wavelength of the coherent light used

m   an integer, which counts the number of lines of interference

Units in the SI system

d, lam in meters

θ degrees

m an integer

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