The ratio of the speed of the electron in the first Bohr orbit of hydrogen and the speed of light is equal to (where `e, h` and `c` have their usual meanings)

Options

A. `2pihc//e^(2)`
B. `er^(2)h//2pic`
C. `e^(2)c//2pih`
D. `2pie^(2)h//hc`

Answer

D

Explanation

`v_(n) = k(2pie^(2))/(nh)`
Take `k =1`
`v_(n) = (2pie^(2))/(nh)`
`v_(1) = (2pie^(2))/(h)`
`(v_(1))/(c ) = (2pie^(2))/(ch)`