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

Explanation

From Bohr.s postulates, the angular momentum is given as
`m v r = (nh)/(2pi)` or `v = (nh)/(2pi mr)`
`n = 4, m = 9.1 xx 10^(-31) kg`,
`r = 0.85 xx 10^(-9) m`
`v = (4 xx 6.625 xx 10^(-34)Js)/(2 xx 3.14 xx 9.1 xx 10^(-31)kg xx 0.85 xx 10^(-9)m)`
The velocity of electron in the 4th orbit `= 5.45 xx 10^(5) ms^(-1)`