Whatis the phase velocity of electromagneticwave having electron density and frequency for D-layer, N = 300 electron/cc, ` nu = 200 kHz ` ?

Options

A. `3 4xx10^(8)` m/s
B. `48xx10^(8)m//s`
C. `3xx10^(7)m//s`
D. `3xx10^(8)m//s`

Answer

B

Explanation

As ` mu = sqrt ( 1 - (8145 N ) /( v^ 2 )) `
` = sqrt ( 1 - (8145 xx 300 xx 10 ^ 6)/( ( 200 xx 10 ^ 3 ) ^ 2 ))`
` = sqrt ( 1- 610875 xx 10 ^( -2 ) ) `
` = sqrt ( 1 - 0.610875) = sqrt ( 0 .389125 ) `
` mu = 0.623 `
Also, ` mu = ( c) /( v) `
` therefore ` Phase velocity,
` v = ( 3 xx 10 ^( 8))/( 0.623 ) = 4.8 xx 10 ^( 8 ) m//s `