What should be the height of transmitting antenna if the T.V. telecast is to cover of a radius of `128 km`?
Radius of earth` = 6.4 xx 10^(6) m`.

Answer

`1280 m`

Explanation

Here , `d = 128 km = 128 xx 10^(3) m`,
`R = 6.4 xx 10^(6) m`
` d = sqrt( 2 R h)`
or ` h = (d^(2))/( 2 R) = ((128 xx 10^(3))^(2))/(2 xx 6.4 xx 10^(6)) = 1280 m`