Question

The frequency and wavelength of EM waves can vary over a wide range of values. Scientists refer to the full range of frequencies that EM radiation can have as the electromagnetic spectrum.

Electromagnetic waves are used extensively in modern technology. Many devices are built to emit and/or receive EM waves at a very specific frequency, or within a narrow band of frequencies. Here are some examples followed by their frequencies of operation:
garage door openers: 40.0 MHz,
standard cordless phones: 40.0 to 50.0 MHz,
baby monitors: 49.0 MHz,
FM radio stations: 88.0 to 108 MHz,
cell phones: 800 to 900 MHz,
Global Positioning System: 1227 to 1575 MHz,
microwave ovens: 2450 MHz,
wireless Internet technology: 2.4 to 2.6 GHz.

Answer 1

All of these technologies uses the technologies of radio waves, including the low
`$\text{frequency}$` microwaves.

The microwave ovens emits in the same frequency band as that some
`$\text{wireless}$` Internet devices.

`$\text{The radiation}$` that is emitted by the wireless Internet devices having the
`$\text{shortest wavelength}$` of all the technologies are listed.

All these technologies emits waves with a wavelength in the range
`$0.10 \ m$` to
`$10 \ m$`.

The
`$\text{earth absorbs}$` the visible light and also
`$\text{emits radiation }$` with a longer
`$\text{wavelength}$`. The earth then absorbs
`$\text{visible light}$` as well as emits the
`$\text{radiation}$` with a
`$\text{lower frequency}$`.