Question

Calculate the maximum slit spacing you can have if you wish to make a double slit interferometer using visible sunlight.

Calculate the number of fringes you will be able to see assuming that the slit spacing is one-half of what you calculated in part (a).

Answer 1

For a double slit set up, the position of first maxima is given by:

=>

the maximum slit spacing can thus be estimated by taking and

therefore, d_max = 750 nm.

ii] If the N is the maximum number of fringes appearing on the screen, theoretically, this Nth fringe will appear at .

here, d = 750nm/2 = 375 nm

so, N = 0.5

therefore, if the slit spacing is reduced to half of the value calculated above, the number of fringes appearing on the screen will be zero [only the central maxima will be present].