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A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required
to receive the signal in line of sight at 4 km distance from it is \mathrm{x\times 10^{-2}}. The value of x is ______.
(Let, radius of earth R = 6400 km)

Option: 1

125


Option: 2

12.5


Option: 3

1250


Option: 4

1.25


Answers (1)

best_answer

\begin{aligned} & \mathrm{d}=\sqrt{2 R \cdot h} \\ & d^2=2 \mathrm{Rh} \\ & (4)^2=2 \times 6400 \times \mathrm{h} \\ \end{aligned}

\begin{aligned} & \frac{16}{2 \times 6400}=h=\frac{1}{800} \mathrm{~km} \\ & \mathrm{~h}=\frac{1000}{800}=\frac{5}{4} \mathrm{~m} \\ & \mathrm{x} \times 10^{-2}=\frac{5}{4} \\ & \mathrm{x}=\frac{500}{4}=125 \end{aligned}

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Ritika Kankaria

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