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PhysicsModern PhysicsAtomic structureEasy2 minPYQ_2020

PhysicsEasysingle choice

If $λ_{1}$ and $λ_{2}$ are the wavelengths of the first members of the Lyman and Paschen series respectively, then $λ_{1} : λ_{2}$ is

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Answer:

Solution:

For first line of Lyman series,

$n_{1}$ = 1 and $n_{2}$ = 2

$∴ \frac{1}{λ_{1}} = R (\frac{1}{1^{2}} - \frac{1}{2^{2}}) = R (1 - \frac{1}{4}) = \frac{3 R}{4}$

For first line of Paschen Series

$n_{1}$ = 3 and $n_{2}$ = 4

$∴ \frac{1}{λ_{2}} = R (\frac{1}{3^{2}} - \frac{1}{4^{2}}) = R (\frac{1}{9} - \frac{1}{16}) = \frac{7 R}{144}$

$∴ \frac{λ_{1}}{λ_{2}} = \frac{7 R}{144} \times \frac{4}{3 R} = \frac{7}{108}$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:Modern PhysicsSubtopic:Atomic structure

⏱ 2mℹ️ Source: PYQ_2020

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