QJEEM12Ph4940: JEE Main 2012 Physics - Class 12 JEEM12Ph4940 Solution: A radar has a power of and is operating at a frequency of It is …

Question

Verified Solution • 2025–26 Session moderate

A radar has a power of

1kW

and is operating at a frequency of

10

GHz.

It is located on a mountain top of height

500

m.

The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth

= 6.4 \times {10^6}m

) is :

Accepted Answer

Let

d

is the maximum distance, upto it the objects

From

\Delta AOC

O{C^2} = A{C^2} + A{O^2}

{\left( {h + R} \right)^2} = {d^2} + {R^2}

\Rightarrow {d^2} = {\left( {h + R} \right)^2} - {R^2}

d = \sqrt {{{\left( {h + R} \right)}^2} - {R^2}}

d = \sqrt {{h^2} + 2hR}

d = \sqrt {{{500}^2} + 2 \times 6.4 \times {{10}^6}} = 80km

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