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Electromagnetic waves of frequencies hig...

Electromagnetic waves of frequencies higher than `9sqrt(2)` MHz are found to be not reflected by the ionosphere on a particular day at a place. The maximum electron density in the ionosphere is :

A

`sqrt2xx10^12//m^3`

B

`sqrt5xx10^12//m^3`

C

`2xx10^12//m^3`

D

`3xx10^12//m^3`

Text Solution

Verified by Experts

The correct Answer is:
C
For ionosphere propagation , the critical frequency is given by `v_c=9sqrt(N_"max")`
where `N_"max"` is the maximum electron density in per `m^3`.
`therefore (N_"max")^(1//2) = v_c/9=(9sqrt2xx10^6)/9=sqrt2xx10^6`
`therefore N_"max" = (sqrt2 xx10^6)^2 = 2xx10^12//m^3`
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