- #1

kihr

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## Homework Statement

Light of two wavelenghts L1 and L2 (L1,L2 = lambda)creates interference fringes in the Young's double slit experiment. To calculate the least distance from the central maximum where the bright fringes for both L1 and L2 coincide. Given: the distance 'd' between the two slits, and 'D' between the plane of the slits and the screen.

## Homework Equations

Distance of the nth bright fringe from the central maximum = nLD/d

For the two bright fringes to overlap,

n1L1 = n2L2 (since D/d is common for both wavelengths)

n1 corresponds to the first wavelength

n2 corresponds to the second wavelength

## The Attempt at a Solution

By the above I am able to get the ratio n1/n2. However, I am unable to proceed any further to determine the required distance to the first point of overlap of the bright fringes.