What is the maximum distance a radar can detect objects on the Earth's surface?

[utkarshakash]

Homework Statement

A radar has power 1kW and is operating at a frequency of 10GHz. It is located on a mountain top of height 500m. The maximum distance upto which it can detect object located on the surface of the earth(Radius of Earth = 6.4*10^6 m) is

Homework Equations

The Attempt at a Solution

I'm not sure what to do here because I'm facing this kind of problem for the first time. Can anyone suggest me some equations to start with?

 

[Rellek]

D = sqrt(2*height*radius) I think

 

[utkarshakash]

D = sqrt(2*height*radius) I think

This gives me the correct answer but how did you think of this? Can you give some references regarding this equation?

 

[BvU]

You google Distance to Horizon