. 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 500m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth = 6.4 x 10m) is

A. 80 km

B. 16 km

C. 40 km

D. 64 km


Best Answer

Ans: A

Sol: |||  Let us assume that the maximum distance on earth where object can be detected is d, then

(h + R)2 = d2 + R2 
h2 + R2 + 2hr = d2 + R2 
 d2 = h2 + 2Rh 


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