Q29. Two wavelengths $\lambda _ { 1 }$ and $\lambda _ { 2 }$ are used in Young's double slit experiment. $\lambda _ { 1 } = 450 \mathrm {~nm}$ and $\lambda _ { 2 } = 650 \mathrm {~nm}$. The minimum order of fringe produced by $\lambda _ { 2 }$ which overlaps with the fringe produced by $\lambda _ { 1 }$ is $n$. The value of $n$ is\\
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