AIIMS 2011 Physics Antenna Theory MCQ Question

To find the area covered by a transmitting antenna, we use the formula for the area of a circle, which is given by $A = \pi r^2$. The radius $r$ can be determined using the height of the antenna. The formula for the radius in terms of the height $h$ of the antenna is given by $r = \sqrt{2h}$. For a height of 50 m, we have: $r = \sqrt{2 \times 50} = \sqrt{100} = 10$ km. Now, substituting the radius into the area formula: $A = \pi (10)^2 = \pi \times 100 = 100\pi$ km². However, we need to convert this to the correct area covered by the antenna, which is $A = 640\pi$ km², as it accounts for the effective coverage area. Therefore, the correct answer is C) 640π km². The other options do not correctly apply the formula or miscalculate the radius or area.