CBSE Class 12 Physics 2019 Delhi Set 3 Paper

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Question : 3
Total: 8
SECTION - B

Obtain the expression for the ratio of the de Broglie wavelengths associated with the electron orbiting in the second and third excited states of hydrogen atom.
Solution:  
2πr=nλ
For second excited state (n=3)
r=0.529(n)2â„«
=0.529(3)2
⇒2π(0.529)(3)2=3λ2
For third excited state n=4
r=0.529(4)2
⇒2π(0.529)(4)2=4λ3
⇒‌
3λ2
4λ3
=‌
(3)2
(4)2

‌
λ2
λ3
=3
:4
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