A sky wave with a frequency 55 MHz is incidnet on D-region of earth's atmosphere at `45^(@)`, The angle of refraction is (electron density for D-region is 400 electron/c.c.

Options

A. 400m
B. `45^(@)`
C. `30^(@)`
D. `15^(@)`

Explanation

For D-region, `v=55xx10^(6)Hz, i=45^(@)`,
`N=400xx10^(6)m^(-3)`
`mu=sqrt(1-(81.45N)/(v^(2))=sqrt(1-(81.45xx400xx10^(6))/((55xx10^(6))^(2))=1`
Also `mu=(sini)/(sin r)`
or `sin i=mu sin r =sin r` or `i=r=45^(@)`