# Problem: An AM radio transmitter broadcasts 25 kW of power uniformly in all directions.a) Assuming all of the radio waves that strike the ground are completely absorbed, and there is no absorption by the atmosphere or other objects, what is the intensity 26 km away?b) What is the maximum electric field strength at this distance, in N/C?

###### FREE Expert Solution

The intensity of electromagnetic radiation:

In terms of the electric field, the average intensity is equal to:

$\overline{){\mathbf{I}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{c}{\mathbf{\mu }}_{\mathbf{0}}}{\mathbf{·}}\frac{{\mathbf{E}}^{\mathbf{2}}}{\mathbf{2}}}$

(a)

Radius, r, from the transmitter = 26 km(1000m/1km) = 26000m

The area is spherical, A = 4πr2 = 4π(26000)2

Power, P = 25kW(1000W/1kW) = 25000 W

###### Problem Details

An AM radio transmitter broadcasts 25 kW of power uniformly in all directions.

a) Assuming all of the radio waves that strike the ground are completely absorbed, and there is no absorption by the atmosphere or other objects, what is the intensity 26 km away?

b) What is the maximum electric field strength at this distance, in N/C?

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