1.

A hydrogen sample is prepared in a particular excited state A of quantum number, n_A = 3 . The ground state energy of hydrogen atom is - |E| . The photons of energy(|E|)/(12) are absorbed in the sample which results in the excitation of some electrons to excited state B of quantum number n_Bwhose value is

Answer»

6
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7

Solution :Given ,
energy of HYDROGEN atom in GROUND state =- | E |and `n_A = 3`
`therefore` Energy of electrons in excited state , `n_A`
`(E )_(n_A) = (-|E|)/(n_A^2)`
Energy of electron in excited state , `n_B`
` = (E )_(n_B) = (-(E ) )/(n_B^2)`
When sample ABSORBS the photon of energy, ` (|E|)/(12)`,
then its electrons REACHES from energy state `n_A ` to energy state `n_B`
Hence , `(E )_(n_B) - (E )_(n_A) = (|E|)/(12)`
`(-|E|)/(n_B^2) - { (-|E|)/(n_A^2) } = (|E|)/(12)`
`(-1)/(n_B^2) + (1)/(n_A^2) = 1/12 rArr - (1)/(n_B^2) = 1/12 - (1)/(n_A^2)`
` =1/12 - 1/9 rArr - (1)/(n_B^2) = 1/12 - (1)/(n_A^2)`
` = 1/12 - 1/9 rArr - (1)/(n_B^2) = - 1/36`
`rArr n_B^2 = 36 `
` therefore n_B = 6`


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