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An outdoor Wi-Fi unit for a picnic area has a 110 mW output and a range of about 38 m. What output power (in mW) would reduce its range to 18 m for use with the same devices as before? Assume there are no obstacles in the way and that microwaves into the ground are simply absorbed.

Respuesta :

Answer:

The output power is 24.68 mW.

Explanation:

Given that,

Power = 110 mW

Range = 38 m

Reduced range = 18 m

We need to calculate the power

Using formula of intensity

[tex]I=\dfrac{P}{A}[/tex]

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

As intensity is constant

[tex]P\propto r^2[/tex]

So, [tex]\dfrac{P_{1}}{P_{2}}=\dfrac{r_{1}^2}{r_{2}^{2}}[/tex]

[tex]P_{2}=\dfrac{r_{2}^2}{r_{1}^{2}}\timesP_{1}[/tex]

Put the value into the formula

[tex]P_{2}=\dfrac{18^2}{38^2}\times110\times10^{-3}[/tex]

[tex]P_{2}=24.68\times10^{-3}\ W[/tex]

[tex]P_{2}=24.68\ mW[/tex]

Hence, The output power is 24.68 mW.

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