<P> Radio waves generally are utilized by antennas of appropriate size (according to the principle of resonance), with wavelengths ranging from hundreds of meters to about one millimeter . They are used for transmission of data, via modulation . Television, mobile phones, wireless networking, and amateur radio all use radio waves . The use of the radio spectrum is regulated by many governments through frequency allocation . </P> <P> Radio waves can be made to carry information by varying a combination of the amplitude, frequency, and phase of the wave within a frequency band . When EM radiation impinges upon a conductor, it couples to the conductor, travels along it, and induces an electric current on the surface of that conductor by exciting the electrons of the conducting material . This effect (the skin effect) is used in antennas . </P> <P> The super-high frequency (SHF) and extremely high frequency (EHF) of microwaves are on the short side of radio waves . Microwaves are waves that are typically short enough (measured in millimeters) to employ tubular metal waveguides of reasonable diameter . Microwave energy is produced with klystron and magnetron tubes, and with solid state diodes such as Gunn and IMPATT devices . Microwaves are absorbed by molecules that have a dipole moment in liquids . In a microwave oven, this effect is used to heat food . Low - intensity microwave radiation is used in Wi - Fi, although this is at intensity levels unable to cause thermal heating . </P> <P> Volumetric heating, as used by microwave ovens, transfers energy through the material electromagnetically, not as a thermal heat flux . The benefit of this is a more uniform heating and reduced heating time; microwaves can heat material in less than 1% of the time of conventional heating methods . </P>

Where does wifi fall on the electromagnetic spectrum