Wave Optics

JEE Main level, numerical answer, medium

57 of 191

Question 57 of 191

Two wavelengths λ1\lambda_1 and λ2\lambda_2 are used in Young's double slit experiment. λ1=450 nm\lambda_1=450 \mathrm{~nm} and λ2=650 nm\lambda_2=650 \mathrm{~nm}. The minimum order of fringe produced by λ2\lambda_2 which overlaps with the fringe produced by λ1\lambda_1 is nn. The value of nn is _____.

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Answer: 9

n2λ2=n1λ1n2n1=λ1λ2=450650=913n2=9\begin{aligned} & \mathrm{n}_2 \lambda_2=\mathrm{n}_1 \lambda_1 \\ & \frac{\mathrm{n}_2}{\mathrm{n}_1}=\frac{\lambda_1}{\lambda_2}=\frac{450}{650}=\frac{9}{13} \\ & \mathrm{n}_2=9\end{aligned}

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