Q. Two light waves of wavelengths $800$ and $600\, nm$ are used in Young's double slit experiment to obtain interference fringes on a screen placed $7 \, m$ away from plane of slits. If the two slits are separated by $0.35 \, mm$, then shortest distance from the central bright maximum to the point where the bright fringes of the two wavelength coincide will be ___$mm$.
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