An electron in a Bohr orbit of hydrogen atom with quantum level `n`, has an angular momentum `4.2178 xx 10^(-34) kg m^(2)s^(-1)`. If this electron drops from this level to the next level, find the wavelength of this spectral line.

Options

A. `18.75 xx 10^(-7)m`
B. `1.87 xx 10^(-7)m`
C. `187.5 xx 10^(-7)m`
D. `0.187 xx 10^(-7)m`

Answer

A

Explanation

`mvr = (nh)/(2pi)` where `n =4, (1)/(lambda) =bar(v) = R_(H) [(1)/(3^(2))-(1)/(4^(2))]`