Question
A radar has a power of 1 Kw and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth = 6.4 x 106 m) is
-
80 km
-
16 km
-
40km
-
64 km
Solution
A.
80 km
Maximum distance on earth where object can be detected is d, then
(h + R)2 = d2 + R2
⇒ d2 = h2 + 2Rh
Since, h<<R,
⇒d2 =2hR
