The velocity of an electron in the first orbit of `H` atom is `v` . The velocity of an electron in the second orbit of `He^(+)` is

Options

A. `2 v`
B. v
C. `(v)/(2)`
D. `(v)/(4)`

Answer

B

Explanation

`v_(n) = alpha ((eZ)/(n))` , were `alpha = (e^(2))/(2 h epsilon_(0)c)` is the constant
`(alpha = (1)/(137))`
`v_(He) = alpha (c(2))/(2) = alpha c`
and `v_(H) = alpha (c(1))/(1) = alpha c = v_(He^+)`