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 up to which it can detect object located on the surface of the earth (Radius of earth = 6.4 × 106 m) is :

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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 up to which it can detect object located on the surface of the earth (Radius of earth = 6.4 × 10⁶ m) is :

64 km

40 km

80 km

16 km

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$d = \sqrt{2 Rh} = \sqrt{2 \times 6 .4 \times 10^{3} \times 0 .5} = 80 km$