Question

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.

Answer 1

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

$I=\dfrac{P}{A}$

$I=\dfrac{P}{\pi r^2}$

As intensity is constant

$P\propto r^2$

So, $\dfrac{P_{1}}{P_{2}}=\dfrac{r_{1}^2}{r_{2}^{2}}$

$P_{2}=\dfrac{r_{2}^2}{r_{1}^{2}}\timesP_{1}$

Put the value into the formula

$P_{2}=\dfrac{18^2}{38^2}\times110\times10^{-3}$

$P_{2}=24.68\times10^{-3}\ W$

$P_{2}=24.68\ mW$

Hence, The output power is 24.68 mW.