QJEEAdv08Ph9dd1: JEE Advanced 2008 Physics - Class 12 JEEAdv08Ph9dd1 Solution: The wavelength of light emitted in the visible region by He +…

Question

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The wavelength of light emitted in the visible region by He $^{+}$ ions after collisions with H atoms is

Accepted Answer

$\frac{h c}{λ} = E_{4} - E_{3}$

$\frac{h c}{λ} = - 13.68 \times 2^{2} (\frac{1}{4^{2}} - \frac{1}{3^{2}})$

$\frac{h c}{λ} = 13.6 \times 2^{2} (\frac{1}{9} - \frac{1}{16})$

$\frac{4.1356 \times 15^{- 15} e V . s \times 3 \times 10^{8} m s^{- 1}}{1} = 2.644$

$\Rightarrow λ ≅ 4.8 * 10^{- 7} m$

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