What is an EM Spectrum?
The electromagnetic spectrum is defined as the distribution of a number of electromagnetic waves as a function of wavelength, frequency, or wave number. The EM wave exhibits both wave-like and particle-like properties. The behaviour of the longest wavelengths is dominated by wave characteristics, whereas the behaviour of the short wavelengths X-rays and gamma rays is dominated by photon aspects, yet the fundamental laws that govern all wavelengths apply to all of them. The wave-particle duality concept that requires both wave and particle characteristics is most frequently encountered in the optical range, a range where the waves are in or near the visible range.
The propagation of light is determined by its wave nature, which is analyzed using Maxwell’s equations. On the other hand, the interaction with matter, which is determined by its particle nature, is analyzed using quantum mechanics. The radiations of the electromagnetic spectrum are characterized by their wavelength λ and frequency ν, which are related by,
where c is the velocity at which electromagnetic radiation propagates in free space, 3 × 108 m/s.
The electromagnetic spectrum exhibits very significant behavioural variations as the frequencies vary from 104 Hz for long radio waves (1 hertz equals one cycle per second) to more than 1021 Hz for commonly encountered gamma rays, the highest energy cosmic gamma rays so far detected reach 1035 Hz (4 x 1020 eV).
The electromagnetic spectrum is a range of all types of electromagnetic radiation, where radio frequencies are placed at the longer end and cosmic rays at the shorter end of the spectrum. This spectrum includes all forms of electromagnetic radiation, such as radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, gamma rays, and their sub-ranges. All of these forms of energy are part of the same spectrum, but they have different properties and applications, including corresponding wavelengths.
The classification of the EM spectrum is based roughly on how the waves are produced or detected.
Here is a list of the different sub-ranges of the Electromagnetic Spectrum, in order of increasing frequency and decreasing wavelength:
Radio waves have the lowest frequency range (3 Hz - 3 GHz) and the longest wavelengths, ranging from more than 100 kilometres to about 10 centimeters. They are used for communication, such as radio and television broadcasts, and for navigation, such as GPS.
Microwaves are the next-highest-frequency waves in the range of 3 GHz - 300 GHz and have wavelengths in the order of 10 centimetres to about a millimeter. They are used for communication, such as cell phone networks and GPS, and also for cooking food.
Infrared radiation are electromagnetic radiations between 300 GHz and 400 THz frequency that have a longer wavelength than visible light, about a millimetre to 750 nm. It is used for heating, such as in infrared saunas, and for night vision.
Visible light have frequency from 400 THz to 790 THz frequency and wavelengths of around 750 nm - 380 nm. It is the only form of electromagnetic radiation that can be seen by the human eye and includes the colors of the rainbow. It is used for illumination, such as in light bulbs, and for photography.
Ultraviolet radiation have shorter wavelengths than visible light, in the order of 380 nm - 10 nm with a frequency range from 790 THz to 30 PHz. It is used for tanning, sterilization, such as in hospitals, and for exposing faults in a material through fluorescence.
X-rays are in the frequency range of 30 PHz - 30 EHz and have shorter wavelengths than ultraviolet radiation, which ranges from 10 nm to 10 pm. They are used for medical imaging, such as X-rays and CT scans, and research in fields such as materials science.
Gamma rays have the highest frequency range (greater than 30 Hz) and shortest wavelengths (less than 10 pm). They are used for medical treatments, such as cancer radiation therapy, and for research, such as imaging and material analysis.
The electromagnetic spectrum is an important part of our lives. It plays a unique role in various scientific and technological fields, and understanding their properties is essential to the development of new technologies. These sub-ranges are also further divided into several sub-ranges based on their frequency and applications.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. These waves are produced by the accelerated motion of charges in conducting wires, cool clouds of gas, and the cosmic microwave background. It can also be created artificially by applying electric current to the antennas, which causes the antennas to vibrate, creating a wave of electromagnetic energy that radiates outward from the antenna. The frequency of the wave determines its wavelength, and the wavelength determines the type of radio wave.
Radio waves are used for variety of purposes, including communication technologies such as radio and television broadcasting. Here are some of the most common sub-ranges of radio waves:
Extremely Low Frequency (ELF) Waves are a sub-range of the radio waves portion of the electromagnetic spectrum that falls within the frequency range from 3 Hz to 3 kHz. They have very low frequencies and extremely long wavelengths of greater than 100 km. These waves are produced by man-made sources such as electric power lines and appliances. They are also produced by a variety of naturally occurring events, including lightning strikes and earth disturbances.
ELF waves are the longest waves that can travel through the atmosphere, water, and solid objects. It covers long distances and are useful for a variety of applications, including:
Very Low Frequency (VLF) Waves are radio waves with a frequency range of 3 kHz - 30 kHz and a corresponding wavelength range from 10 km to 100 km. These are generated by natural sources such as lightning and by man-made sources such as nuclear explosions.
These VLF waves are used for time signal broadcasting, scientific research, communication with submarines, and navigation systems. Due to its constrained bandwidth, VLF is often used for coded communications with low data rates, such as underwater communication, making it impracticable for audio transmission. These waves can also penetrate dirt and rock for some distance. Long-range and steady-phase properties are advantageous for VLF frequencies.
VLF waves are used in a variety of applications, including:
Low - Frequency (LF) Waves are radio waves with a frequency range of 30 kHz - 300 kHz and a corresponding wavelength range from 1 m to 10 km. These can be generated by man-made sources, such as radio transmitters. They are also generated by the Earth's magnetic field, which is composed of a variety of frequencies.
They are used in a variety of applications, including navigation systems and other applications such as:
Medium-Frequency (MF) Waves are radio waves with a frequency range of 300 kHz - 3 MHz and a corresponding wavelength range from 100 m to 1 km. These waves fall between the low-frequency (LF) and high-frequency (HF) bands of the electromagnetic spectrum.
Most common applications of MF waves include:
High-Frequency (HF) Waves are waves with a frequency range of 3 MHz - 30 MHz and a corresponding wavelength range from 10 m to 100 m. These are generated by natural sources like the sun and lightning, which produce a wide range of frequencies, including HF waves.
Applications of HF wave include:
Very High-Frequency (VHF) Waves are radio waves in the frequency range of 30 MHz - 300 MHz with a corresponding wavelength range from 1 m to 10 m. These are most suitable for short-distance terrestrial communication, such as within a city or town. VHF waves are also able to penetrate through buildings and other obstacles, making them useful for two-way radio communication.
Ultra High Frequency (UHF) Waves are radio frequencies in the range of 300 MHz - 3 GHz with a corresponding short wavelength range from 10 cm to 1 m. This makes them ideal for transmitting signals over short distances, such as within a building or across a city. UHF waves are also able to penetrate walls and other obstacles, making them useful for wireless communication.
Microwave radiation is commonly referred to as "microwaves." They are short-wavelength radio waves with frequencies in the gigahertz (GHz) range that have a slightly higher frequency than radio waves. In the electromagnetic spectrum, they are located between radio waves and infrared radiation. Low-frequency radio waves and microwaves both operate on the same fundamental principle. These waves are distinguished from radio waves because of the technologies used to access them. They are produced by special vacuum tubes (called klystrons, magnetrons, and Gunn diodes).
Microwaves that have a specific wavelength can travel through the earth's atmosphere and are useful in transmitting information to and from satellites in orbit. The satellite dishes are therefore made of metal since it effectively reflects microwaves. Certain frequencies of microwaves are absorbed by water, which is useful in cooking. Wave phenomena such as diffraction, refraction, interference, and reflection can impact the transmission of microwaves. It can pass through glass and plastic, which is why it is good to use a plastic or glass container in a microwave oven.
These waves are a form of non-ionizing radiation, meaning they do not have enough energy to cause damage to living cells. They are used in a variety of communication applications, such as radar systems, medical imaging, and industrial processes such as drying and curing materials and heating. Microwave ovens use microwaves to heat food quickly and evenly.
Here are some of the most common sub-ranges of Microwaves:
SHF (Super High Frequency) are electromagnetic waves that have a frequency range from 3 GHz to 30 GHz. This range of frequencies is a part of the high-frequency (HF) radio spectrum. These waves are generated by transmitting antennas and are used for two-way communication. They are also used for short-range wireless communication, such as Bluetooth and Wi-Fi. It can travel long distances, but it can be blocked or reflected by obstacles in its path, such as mountains and buildings.
SHF waves are used in a wide range of applications, including:
They have a high data rate and are capable of carrying large amounts of information. These waves are relatively inexpensive to use, and they can be used to communicate over long distances. However, they are vulnerable to interference from other radio signals and can be affected by atmospheric conditions. These waves are also more expensive than lower-frequency waves, such as ultra-high-frequency (UHF) waves.
Extremely high frequency (EHF) waves are microwaves with a relatively short wavelength that have a frequency range between 30 GHz and 300 GHz. These waves have the shortest wavelengths out of any EM waves, can travel through space at the speed of light, and can be used to transmit data over large distances.
Ka-Band microwaves are in the frequency range from 27 GHz to 40 GHz. This technology has been developed in the late 1990s. The higher frequency of this band allows more data to be transmitted in a shorter amount of time. They are also more efficient than other microwave frequencies, meaning that they require less power to transmit the same amount of data.
V-Band microwaves are part of the microwave frequency spectrum, which ranges from 1 GHz to 300 GHz. They are typically used in the range of 40 GHz - 75 GHz.
W-Band microwaves are a type of electromagnetic radiation that has a frequency of 75 GHz - 110 GHz, which is in the millimeter-wave range.
G-Band microwaves are a type of microwave radiation that has a high-frequency range from 110 GHz to 300 GHz. These frequency ranges are higher than those used for other types of microwave radiation, such as X-band and Ku-band. These microwaves are also known as millimeter-wave radiation because they have a wavelength of between 1 and 10 millimeters.
Infrared radiation are a type of electromagnetic radiation that lies between visible light and microwaves in the electromagnetic spectrum. They have a longer wavelength than visible light but a lower frequency than microwaves. They are invisible to the human eye but can be detected by special instruments such as infrared cameras. Infrared radiation is produced by all objects that have a temperature above absolute zero. The hotter an object is, the more infrared radiation it emits.
Infrared radiation is used in a variety of applications, including:
Far Infrared (FIR) are a type of electromagnetic radiation on the electromagnetic spectrum with a frequency range from 300 GHz to 20 THz. They have a longer wavelength than visible light but a shorter wavelength than microwaves, which are from 15 μm - 1,000 μm. FIR is invisible to the human eye but can be detected by special cameras and sensors.
FIR are used in a variety of applications, including:
Long-Wavelength Infrared (LWIR) are a type of electromagnetic radiation that falls within the infrared portion of the electromagnetic spectrum with a frequency range of 20 THz - 37 THz and a corresponding wavelength range from 8 μm to 14 μm. They are also known as thermal infrared radiation.
LWIR are used in a variety of applications, including:
Mid-Wavelength Infrared (MWIR) are a part of the electromagnetic spectrum that lies between the visible and far infrared regions with a frequency range of 37 THz - 100 THz and a corresponding wavelength range from 3 μm to 5 μm. They are a type of infrared radiation that is emitted by objects that are warmer than their surroundings. These radiations are invisible to the human eye but can be detected by special cameras and sensors.
MWIR are used in a variety of applications, including:
Short-Wavelength Infrared (SWIR) are a part of the electromagnetic spectrum that lies between visible light and mid-infrared. They are typically defined as having a frequency range of 100 THz - 214 THz and corresponding wavelengths from 0.9 to 1.7 micrometers.
SWIR are used in a variety of applications, including imaging, sensing, and communication.
Near Infrared (NIR) are a part of the electromagnetic spectrum that lies between visible light and microwave radiation with a frequency range of 214 THz - 400 THz and a corresponding wavelength range from 0.7 to 1.3 micrometers. NIR is often referred to as “near-infrared” because it is close to the visible spectrum. It is invisible to the human eye but can be detected by certain types of cameras.
NIR are used in a variety of applications, including:
Visible light is a form of electromagnetic radiation that is visible to the human eye. The small portion of this electromagnetic spectrum is produced by the sun, stars, and other sources of light. They are also produced by electric sparks, fluorescent and incandescent light bulbs, and other sources of artificial light. This electromagnetic spectrum is made up of different colors of the rainbow, each with its own wavelength. Red has the longest wavelength, while violet has the shortest.
Visible light is also used in many scientific and technological applications. They are used in microscopes to magnify objects and in telescopes to observe distant objects in space. They are also used in fiber optics, which is a technology used to transmit data over long distances. The visible spectrum can be further divided into several sub-ranges based on the different colors that make up the visible light spectrum:
Red light has the longest wavelength of all visible light and the lowest frequency. This means that it has the least amount of energy compared to other colors of visible light. Red light has a wavelength of around 700 nanometers, and its frequency is between 400 and 480 terahertz. Red light is located at the lower end of the spectrum, just above infrared.
Red light has many uses in the modern world such as:
Orange light in the electromagnetic spectrum is a type of light that is visible to the human eye. It has located between red and yellow on the visible spectrum with a frequency of 480 THz - 510 THz and wavelength of approximately 590 to 620 nanometers.
Yellow light in the electromagnetic spectrum is a type of visible light that is located between the green and orange colors. It has a frequency range of 510 - 530 THz and corresponding wavelength of 570 nm - 590 nm and is one of the most common colors in nature. This light is produced by the sun and is the most common color in the visible spectrum. It is also the most common color in the natural environment, as it is the color of the sky during the day. This light is also used in many applications, such as:
Green light is a type of electromagnetic radiation that is part of the visible light spectrum. It has a frequency range of 530 THz - 580 THz and a wavelength of approximately 520 nm - 570 nm and is located between blue and yellow on the visible light spectrum. This light is the most abundant color in the visible light spectrum and is the color most commonly associated with nature. It is produced by a variety of sources, including fluorescent lights and LED lights.
Green light is used in many applications, including:
Blue light is a type of electromagnetic radiation that is part of the visible light spectrum. It has a frequency range of 580 THz - 675 THz and a wavelength of between 380 and 500 nanometers, which is shorter than other visible light colors such as red, orange, yellow, and green. This spectrum of light is the most energetic visible light is the most likely to cause damage to the eyes, mostly because it is emitted from digital screens, such as computers, tablets, and smartphones. It is also emitted from LED and fluorescent lights. This light has many uses including:
Violet light is a type of light that is found in the visible spectrum of light. It has a frequency range of 675 THz - 790 THz and a corresponding wavelength of approximately 380 - 450 nm and is the highest energy visible light. It has the shortest wavelength of visible light and is often referred to as "purple" light.
Violet light has many uses in science and technology including:
Ultraviolet (UV) Radiation
Ultraviolet (UV) radiations are a type of electromagnetic radiation that lies between visible light and X-rays on the electromagnetic spectrum. They have a shorter wavelength and higher frequency than visible light. These are invisible to the human eye but can be detected by certain types of sensors. UV radiation are produced naturally by the sun and can also be produced by artificial sources such as tanning beds and welding arcs.
Exposure to UV radiation can have both positive and negative effects on human health. On the positive side, UV radiation helps the body produce vitamin D, which is essential for healthy bones and teeth. On the negative side, too much exposure to UV radiation can cause sunburns, skin cancer, and eye damage.
This spectrum can be further divided into three sub-ranges:
UV-A rays are a type of ultraviolet radiation that is emitted from the sun with a frequency range of 790 - 940 THz and a corresponding wavelength range from 320 nm to 400 nm. They have the longest wavelength of ultraviolet radiation and the least amount of energy. These rays are also known as "black lights" because they are invisible to the human eye.
They are used for black light applications, such as in advertising displays and artistic performances. These ultraviolet radiations are the most abundant type of ultraviolet radiation and make up 95% of the UV rays that reach the Earth's surface. They can also be used for beneficial purposes such as:
UV-B rays are electromagnetic waves with a frequency range of 940 THz - 1 PHz and a wavelength range from 280 nm to 320 nm. UVB rays are the most damaging type of UV radiation because they penetrate the skin more deeply than UVA rays. They are used in science and technology including:
UV-C rays are a type of ultraviolet radiation that is found in sunlight with a frequency range of 1 PHz - 30 PHz and a wavelength range from 100 nm to 280 nm. They are the shortest and most energetic of the three types of ultraviolet radiation, and they have the highest energy level. These rays are not visible to the human eye but they can cause skin damage and other health problems if exposed to them for too long.
These rays have applications including:
X-rays are a type of electromagnetic radiation, just like visible light, radio waves, and gamma rays, which have a higher frequency and shorter wavelength than ultraviolet radiation. These rays were discovered in 1895 by German physicist Wilhelm Röntgen. He noticed that a fluorescent screen near a cathode ray tube glowed when the tube was turned on. He called the mysterious rays “X-rays” because they were unknown at the time.
They have a higher frequency and shorter wavelength than visible light, and they have the ability to penetrate solid objects. These rays have applications including:
Here are some of the most common sub-ranges of X-rays:
Extreme Ultra Violet (EUV) X-rays are a type of electromagnetic radiation that lies in a frequency range of 30 PHz - 30 EHz with a wavelength ranging from 0.01 nm to 10 nm. These X-rays are invisible to the human eye but can be detected by special instruments. They are produced by high-energy processes in the universe such as the collision of particles in the solar wind or the emission of radiation from stars and galaxies.
EUV X-rays are important for a variety of scientific and technological applications including:
Soft X-rays are a type of electromagnetic radiation that lies in the frequency range of 30 PHz - 3 EHz and wavelength range from 0.1 nm to 10 nm. They are produced by a variety of sources, including the sun, stars, and black holes. These X-rays are also produced in laboratory settings, such as in X-ray tubes and synchrotrons.
Soft X-rays are used in a variety of applications, including:
Hard X-rays are a type of electromagnetic radiation with a frequency range of 3 EHz - 30 EHz and a wavelength range from 0.01 nm to 0.1 nm. These are produced when high-energy particles, such as electrons, protons, and neutrons, interact with matter. When these particles collide with atoms, they can cause the atom to emit X-rays. The energy of the X-rays is determined by the energy of the particles that produced them. The higher the energy of the particles, the higher the energy of the X-rays. They have more energy than soft X-rays and are capable of penetrating materials that are opaque to visible light. These rays have applications including:
Gamma rays are defined as electromagnetic radiation with the highest frequency and shortest wavelengths. They do not have distinct sub-ranges and are the most energetic form of light. They are produced by a variety of sources, including cosmic rays, radioactive decay, and the explosion of nuclear reactions. These can also be produced as a result of some medical treatments, such as radiation therapy.
Gamma rays play a critical role in fields such as:
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