Light vs Radio Waves
Energy is one of the primary constituents of the universe. It is conserved throughout the physical universe, never created or never destroyed but transforming from one form to another. Human technology, primarily, is based on the knowledge of methods to manipulate these forms to produce a desired outcome. In physics, energy is one of the core concepts of investigation, along with matter. Electromagnetic radiation was comprehensively explained by physicist James Clarke Maxwell in 1860`s.
Electromagnetic radiation can be considered as a transverse wave, where an electric field and a magnetic field oscillate in perpendicular to each other, and to the direction of propagation. The energy of the wave is in the electric and the magnetic fields and, therefore, the electromagnetic waves require no medium for propagation. In a vacuum, electromagnetic waves travel at the speed of light, which is a constant (2.9979 x 108 ms-1). The intensity/strength of the electric field and the magnetic field has a constant ratio, and they oscillate in phase. (i.e. the peaks and the troughs are occurring at the same time during propagation)
The electromagnetic waves have different wavelengths and frequencies. Based on the frequency, the properties displayed by these waves differ. Therefore, we have named different frequency ranges with different names. Light and radio waves are two ranges of electromagnetic radiation with different frequencies. When all the waves are listed in ascending or descending order, we call it the electromagnetic spectrum.
Light is the electromagnetic radiation between the wavelengths 380 nm to 740 nm. It is the range of the spectrum to which our eyes are sensitive. Therefore, humans see things using the visible light. The color perception of the human eye is based on the frequency/ wavelength of light.
With the increase in frequency (decrease in the wavelength), the colors vary from red to violet as shown in the diagram.
The region beyond the violet light in the EM spectrum is known as the ultra violet (UV). The region below the red region is known as the Infrared, and thermal radiation occurs in this region.
The sun emits most of its energy as UV and visible light. Therefore, life developed on earth has a very close relationship to the visible light as an energy source, media for visual perception, and many other things.
The region is the EM spectrum below the infrared region is known as the Radio region. This region has wavelengths from 1mm to 100km (the corresponding frequencies are from 300 GHz to 3 kHz). This region is further divided into several regions as given in the table below. Radio waves are basically used for communication, scanning, and imaging processes.
Frequency and wavelength in the air
Tremendously low frequency
< 3 Hz
> 100,000 km
Natural and man-made electromagnetic noise
Extremely low frequency
100,000 km – 10,000 km
Communication with submarines
Super low frequency
10,000 km – 1000 km
Communication with submarines
Ultra low frequency
1000 km – 100 km
Submarine communication, Communication within mines
Very low frequency
100 km – 10 km
Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics
10 km – 1 km
Navigation, time signals, AM long wave broadcasting (Europe and parts of Asia), RFID, amateur radio
1 km – 100 m
AM (medium-wave) broadcasts, amateur radio, avalanche beacons
100 m – 10 m
Shortwave broadcasts, citizens’ band radio, amateur radio and over-the-horizon aviation communications, RFID, Over-the-horizon radar, Automatic link establishment (ALE) / Near Vertical Incidence Skywave (NVIS) radio communications, Marine and mobile radio telephony
Very high frequency
10 m – 1 m
FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land Mobile and Maritime Mobile communications, amateur radio, weather radio
Ultra high frequency
1 m – 100 mm
Television broadcasts, microwave ovens, microwave devices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as Land Mobile, FRS and GMRS radios, amateur radio
Super high frequency
100 mm – 10 mm
Radio astronomy, microwave devices/communications, wireless LAN, most modern radars, communications satellites, satellite television broadcasting, DBS, amateur radio
Extremely high frequency
10 mm – 1 mm
Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio, directed-energy weapon, millimeter wave scanner
Terahertz or Tremendously high frequency
THz or THF
300–3,000 GHz1 mm – 100 μm
Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensed-matter physics, terahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio
What is the difference between Light Wave and Radio wave?
• The radio waves and light are both electromagnetic radiations.
• Light is emitted from a relatively higher energy source/ transition than the radio waves.
• Light has higher frequencies than radio waves and has shorter wavelengths.
• Both light and radio waves display usual properties of waves, such as reflection, refraction, and so forth. However, the behavior of each property is dependent on the wavelength/ frequency of the wave.
• Light is a narrow band of frequency in the EM spectrum while radio occupies a large portion of the EM spectrum, which is further divided into different regions based on the frequencies.