At a distance of 10 km from a radio transmitter, the amplitude of the E-field is 0.20 volts/meter. What is the total power emitted by the radio transmitter

Respuesta :

Answer:

The total power is  [tex]P = 6.665 *10^{4} \ W[/tex]        

Explanation:

From the question we are told that

     The distance is  [tex]r = 10 \ km = 1000 \ m[/tex]

      The amplitude of the electric field is   [tex]E = 0.20 \ volt/meter[/tex]

Generally the average intensity of the electromagnetic field from the radio transmitter is mathematically represented  as

           [tex]I = \frac{E^2}{ 2 \mu_o * c }[/tex]

Here c is the speed of light with value  [tex]c = 3.0 *10^{8} \ m/s[/tex]

         [tex]\mu_o[/tex] is the permeability of free space with value  [tex]\mu_o = 4\pi *10^{-7} \ N/A^2[/tex]

So

           [tex]I = \frac{0.2^2}{ 2 * 4\pi *10^{-7} * 3.0*10^{8} }[/tex]      

=>        [tex]I = 5.307 *10^{-5} \ W/m^2[/tex]

Generally this intensity can also be mathematically represented as

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

=>           [tex]P = I ( 4 \pi r^2 )[/tex]        

=>           [tex]P = 5.307 *10^{-5} ( 4 * 3.142 * 1000^2 )[/tex]        

=>           [tex]P = 6.665 *10^{4} \ W[/tex]        

The total power emitted by the radio transmitter is [tex]6.67\times 10^4 \ W[/tex].

The given parameters;

  • amplitude of the electric field, E = 0.2 V/m
  • distance of the transmitter, = 10 km = 10,000 m

The intensity of the radio wave from the transmitter is calculated as follows;

[tex]I = \frac{E^2}{2\mu_0 c} \\\\I = \frac{0.2^2 }{2\times 4\pi \times 10^{-7} \times 3\times 10^8} \\\\I = 5.305 \times 10^{-5} \ W/m^2[/tex]

The total power emitted by the radio transmitter is calculated as follows;

[tex]I = \frac{P}{A} \\\\P = IA\\\\P = I \times 4\pi r^2\\\\P = (5.305\times 10^{-5} )\times 4\pi \times (10,000)^2\\\\P = 6.67\times 10^{4} \ W[/tex]

Thus, the total power emitted by the radio transmitter is [tex]6.67\times 10^4 \ W[/tex].

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