Welcome to Westonci.ca, where finding answers to your questions is made simple by our community of experts. Discover comprehensive solutions to your questions from a wide network of experts on our user-friendly platform. Connect with a community of professionals ready to help you find accurate solutions to your questions quickly and efficiently.

A radio antenna broadcasts a 1.0 MHz radio wave with 20.0 kW of power. Assume that the radiation is emitted uniformly in all directions.
1) What is the wave's intensity 30 km from the antenna
2) What is the electric field amplitude at this distance?

Sagot :

Answer:

1) [tex]I=1.8*10^{-6}\: W/m^{2}[/tex]  

2) [tex]E=0.037 \: V/m[/tex]

Explanation:

1)

The intensity equation is given by:

[tex]I=\frac{P}{4\pi r^{2}}[/tex]

Where:

  • P is the power of the radio wave
  • r is the distance from the source

[tex]I=\frac{20000}{4\pi (30000)^{2}}[/tex]

[tex]I=1.8*10^{-6}\: W/m^{2}[/tex]  

2)

Now, the intensity and the electric field are related as:

[tex] I=0.5c\epsilon_{0}E^{2}[/tex]

Here:

  • c is the speed of light
  • ε₀ is the electric permittivity
  • E is the electric field

We need to solve it for E.

[tex]E= \sqrt{\frac{2I}{c\epsilon_{0}}}[/tex]

[tex]E= \sqrt{\frac{2(1.8*10^{-6})}{(3*10^{8})(8.85*10^{-12})}}[/tex]

[tex]E=0.037 \: V/m[/tex]

I hope it helps you!