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

The output power is 24.68 mW.

Step-by-step explanation:

Given that,

Power = 110 mW

Range = 38 m

Reduced range = 18 m

We need to calculate the power

Using formula of intensity

`I=(P)/(A)`

`I=(P)/(\pi r^2)`

As intensity is constant

`P\propto r^2`

So,
`(P_(1))/(P_(2))=(r_(1)^2)/(r_(2)^(2))`

`P_(2)=(r_(2)^2)/(r_(1)^(2))*P_(1)`

Put the value into the formula

`P_(2)=(18^2)/(38^2)*110*10^(-3)`

`P_(2)=24.68*10^(-3)\ W`

`P_(2)=24.68\ mW`

Hence, The output power is 24.68 mW.