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Wave Optics

Question
CBSEENPH12038571

(a) Using the Bohr's model calculate the speed of the electron in a hydrogen atom in the n = 1, 2, and 3 levels. (b) Calculate the orbital period in each of these levels.

Solution

(a) From the relation, 

v = cnα,      where   α = 2π Ke2ch = 0.0073

Therefore, the speed of electron in hydrogen atom in n=1, 2 and 3 is given by, 
                    v1 = 3×1081×0.0073 = 2.19×106 m/sv2 = 3×1082×0.0073 = 1.095 ×106 m/sv3 =3×1083×0.0073 =7.3×105 m/s.

(b) Orbital period in each of the level is given by, 

T = 2πrv  As  r1 = 0.53×10-10m  

T1 = 2π×0.53×10-102.19×106= 1.52×10-16s ' 

As,  r2 = 4 r1    and   v2  = 12v1 

         T2 =  8 T1      = 8 × 1.52 × 10-16s      = 1.216 × 10-15s 

Also as, r3 = 9 r1   and  v3 = 13v1 
 T3 = 27 T1 = 27 × 1.52 × 10-16s                      = 4.1 × 10-15 s. 

T1, T2 and T3 are respectively the orbital time period for n1, nand n3