Find out the number of waves made by a Bohr's electron in one complete revolution in its `3rd` orbit.

Explanation

In general, the number of waves in any orbit is
Number of waves = `("Circumference of orbit")/("Wavelength")`
`= (2 pi r)/(lambda)`
But `lambda = h/(mv)`
No. of waves = `(2 pi r)/(h//mv) = (2 pi r. mv)/(h)`
or ` = (2 pi (mvr))/(h)`
the angular momentum of Bohr.s 3rd orbit is
`mvr = (3h)/(2pi)`
`:.` No. of waves = `(2pi)/h xx (3h)/(2pi) = 3`.
No. of waves in Bohr.s 3rd orbit = 3.