JEE Main 2017 · 2 Apr · Shift 1 · Physics Q25

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Some energy levels of a molecule are shown in the figure. The ratio of the wavelengths $r=\lambda_1/\lambda_2$ , is given by :

Energy levels −E, −4E/3 (dashed), −2E and −3E. λ₂ is the transition from −E to −4E/3; λ₁ is the transition from −E to −2E.

r=\dfrac43

r=\dfrac23

r=\dfrac34

r=\dfrac13

Answer and worked solution

Official answer: D

$\lambda_1$ is the transition $-E\to-2E$ , energy $E$ . $\lambda_2$ is $-E\to-\frac43E$ , energy $\frac E3$ . So
$r=\frac{\lambda_1}{\lambda_2}=\frac{E/3}E=\frac13.$

Topics:Bohr model and hydrogen spectrum

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JEE Main 2017 · 2 Apr · Shift 1, Physics question 25