JEE Main 2012 — Communication System Question with Solution
JEE Main 2012 (Offline)
Question
A radar has a power of and is operating at a frequency of . It is located on a mountain top of height . The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth ) is
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Show full solutionCorrect option: A
Correct answer
A
Step-by-step explanation
Maximum distance on earth where object can be detected is , then
$\begin{array}{ll}
& (h+R)^2=d^2+R^2 \\
\Rightarrow & d^2=h^2+2 R h \\
\text { since } & h < < R, \quad \Rightarrow d^2=2 h R \\
\Rightarrow & d=\sqrt{2(500)\left(6.4 \times 10^6\right)}=80 \mathrm{~km}
\end{array}$
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This is a previous-year question from JEE Main 2012, covering the Communication System chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.