A ratio has a power of `1 kW` and is operating at a frequency of `10 GHz` it is located on a mountain top of beigh `500 m ` The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth ` = 6.4 xx 10^(6) m )` is

Options

A. 80 km
B. 16 km
C. 40 km
D. 64 km

Answer

A

Explanation

`r=R+hR`
`x=sqrt((R+h)^(2)-R^(2))`
`sqrt(h^(2)+2hR)`
`x^(2)=25000+2.500 6.4 100000`
`=25000+(64xx100000000)`
`=10^(4)(640025)`
`x^(2)=10^(4)640000rArr x=8xx10^(4)m=80km`.