Question

In short wave communication waves of which of the following frequeuncies will be reflected back by the ionospheric layer having electron density `10^(11)per m^(3)`?
A. `18 MHz`
B. `10 MHz`
C. `12 MHz`
D. `2 MHz`

Answer 1

Correct Answer - D
The perceived frequency of sky wave for reflection from an ionospheric layer is `v_(c)=9n^(1/2)`
where `n` is the number density of electrons `//m^(3)`.
Given, `n=10^(11)//m^(3)`
`:. v_(c)=9xx(10^(11))^(1/2)=2.8 MHz~~2MHz`
do not satisfy this condition.