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Question
The light emitted in the transition n = 3 to n = 2 in hydrogen is called Hα light. Find the maximum work function a metal can have so that Hα light can emit photoelectrons from it.
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Solution
The Hα light can emit the photoelectrons if its energy is greater than or equal to the work function of the metal.
Energy possessed by Hα light (E) is given by
`E = 13.6 (1/n_1^2 - 1/n_2^2)eV`
`Here , n_1 = 2 , n_2 = 3`
`therefore E = 13.6 xx (1/4 - 1/4 )`
= `(13.6xx5)/36 = 1.89 eV`
= 1.90 eV
Hα light will be able to emit electron from the metal surface for the maximum work function of metal to be 1.90 eV.
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