The radius of the fourth orbit in hydrogen atom is 0.85 nm. Calculate the velocity of the electron in this orbit.

The radius of the fourth orbit in hydrogen atom is 0.85 nm. Calculate

1.	The radius of the fourth orbit in hydrogen atom is 0.85 nm. Calculate the velocity of the electron in this orbit.
Answer» Solution :From Bohr.s postulates, the angular momentum is given as `mvr=(nh)/(2pi) or v=(nh)/(2pimr)` `n=4, m=9.1xx10^(-31)KG`. `r=0.85xx10^(-9)m` `v=(4xx6.625xx10^(-34)Js)/(2xx3.14xx9.1xx10^(-31)kgxx0.85xx10^(-9)m)` The velocity of electron in the 4th orbit `=5.45xx10^(5)ms^(-1)`