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QJEEM21Ph4218: JEE Main 2021 Physics - Class 12 JEEM21Ph4218 Solution: Two identical antennas mounted on identical towers are…

Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 km)

Multiple Choice Options

  • A 158.2 m
  • B 79.1 m
  • C 19.77 m
  • D 39.55 m

Step-by-Step Verified Solution

JEE Main 2021 (Online) 16th March Evening Shift Physics - Communication Systems Question 65 English Explanation

Let minimum height of receiving antenna = h2

∴\therefore d=2Rh1+2Rh2d = \sqrt {2R{h_1}} + \sqrt {2R{h_2}}

=22Rh= 2\sqrt {2Rh} [given : h1=h2=h{h_1} = {h_2} = h ]

⇒h=d28R\Rightarrow h = {{{d^2}} \over {8R}}

=45×458×6400= {{45 \times 45} \over {8 \times 6400}} Km

=0.03955= 0.03955 Km

=39.55= 39.55 m

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