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Wave Optics

Question
CBSEENPH12038601

A hydrogen atom initially in the ground state absorbs a photon; which excites it to the n = 4 level. Determine the wavelength and frequency of photon.

Solution

Initially, hydrogen atom is in the ground state. 
After absorption of photon, atom is excited to n=4th level.

USing the Rydberg's formula,
             1λ = R1n12-1n22

we have,   
             1λ = 1.09 × 107 112-142       = 1.09 × 107 × 1516

          λ = 161.09 × 107 × 15   = 9.8 × 10-8m is the wavelength of the photon.


   Frequency of the photon, ν is given by,
 
          v = cλ = 3 × 1089.8 × 10-8                = 3.06 × 1015 s-1.