Electromagnetic radiation

Electromagnetic Radiation

In classical physics, electromagnetic radiation is defined as the movement of energy through free space or a material medium at the speed of light in the form of electric and magnetic fields, which combine to generate electromagnetic waves such as gamma rays, visible light, and radio waves. There is a synchronization of electric and magnetic fields in the electromagnetic waves. The speed of light c is the same as the speed of electromagnetic waves. Perpendicular to the fields, a wave propagates in isotropic and homogeneous mediums. As a transverse wave, these fields are perpendicular to one another. When electromagnetic waves are emitted from a single point source, the wavefront has the appearance of a sphere. Electromagnetic waves are classified by their frequency and wavelength in the electromagnetic spectrum. Electromagnetic waves of different frequencies have distinct names based on where they originate and how they affect the environment.

According to contemporary quantum theory, electromagnetic radiation is the flow of photons (also known as light quanta) through space. Photons are energy particles that travel at the speed of light at all times. The sign h stands for Planck's constant, and the value of v is equal to the frequency of an electromagnetic wave in classical theory. All photons with the same energy h are similar, and their numerical density is proportional to the radiation's intensity. When electromagnetic radiation interacts with charged particles in atoms, molecules, and bigger objects of matter, it encompasses a set of characteristics. These characteristics, the methods of generating and monitoring electromagnetic radiation, the way it happens naturally, and its technological applications are all dependent on its frequency.

Occurrence and Importance

Electromagnetic radiation accounts for about 0.01% of the total mass/energy of the universe. It permeates many aspects of human life, and current communications technology and health care rely heavily on one or more of its manifestations. Most species' eyes, including humans, are used to being sensitive to and thus see the most plentiful component of the Sun's electromagnetic radiation—light, which constitutes the visible portion of the Sun's broad spectrum of frequencies. Additionally, green plants exhibit high responsiveness to the high intensity of solar electromagnetic radiation, which is absorbed by a chemical called chlorophyll, required for photosynthesis-based plant growth. Almost all of the fuels used in the 21st century, including gas, oil, and coal, are stored forms of energy received from the sun centuries ago as electromagnetic radiation.

Properties

Electromagnetism is a physical phenomenon that exemplifies the electrodynamics theory. The electric and magnetic fields operate on the superposition principle. A time-varying electric or magnetic field, or a field generated by any particular particle, adds to the fields already present in the area from other sources. The magnetic and electric fields are vector fields; hence, these two fields' combination follows the same rules. A constructive or destructive interference pattern is formed when two or more coherent light waves interact. The resulting irradiation is different from the sum of the individual overlapping light waves' constituent irradiances. When the electromagnetic field moves through static and magnetic fields in a medium that moves in a straight line, like a vacuum, they don't change. In the case of non-linear media, there is a chance for some interaction. Light and static magnetic or electric fields interact in media such as certain crystals through the Faraday and Kerr effects.

When a light wave refracts, it does so via two distinct mediums of varying densities. The light wave's speed and direction change as a result of this. Snell's law states that the ratio of the two media's refractive indices determines how much the path changes. Compound wavelengths make up most of the light we see in the daylight. When light travels through a prism, it splits into a range of colors that can be seen with the naked eye. As a result, the wavelength of the light traveling through the prism affects its refractive index. As a result, the components of sunlight undergo varying degrees of bending, resulting in a spectrum.

Wave Model

As a homogeneous, isotropic medium, electromagnetic radiation travels in transverse waves. A transverse amplitude wave shows an energy transfer path perpendicular to the wave's oscillations. The electric and magnetic fields are synchronized. They both reach their highest and lowest peaks at the same time. There is a widespread belief that the two fields are not in sync. That's because one feeds off the other in a mutually exclusive manner. The electric and magnetic fields can have a phase difference if the fields are sinusoidal functions. Near-field antennas are affected by this. Far-field electromagnetic radiation has a time-space relationship, which means that the time difference between one type of field and the other is proportionate. This necessitates that both fields be in sync. The crests and troughs of a monochromatic wave, which refers to an electromagnetic wave with a single frequency, are cyclical in nature. The wavelength is defined as the distance between two successive troughs or crests. The wavelengths of electromagnetic waves are determined by their size. The frequency has an inverse relationship with the electromagnetic wave's wavelength.

Particle Model

The black body radiation was shown to be incompatible with the wave model of light. Max Planck, a scientist, proposed the hypothesis of black-body radiation in 1900. This theory provided an explanation for the observed spectrum. The hypothesis is predicated on the assumption that light is emitted in discrete packets of energy. These energy bundles are quanta of energy. Albert Einstein linked light quanta to original particles in 1905. For this reason, the light particle was referred to as a photon, a nod to electrons and protons at the time. The photon's energy is proportional to the wave's frequency. The photoelectric effect was a strange phenomenon that light's wave nature couldn't explain. This experiment convinced Einstein that light was made up of particles. When a specific frequency of light strikes a metal surface, electrons are expelled from it. When a voltage is placed across, this results in the flow of an electric current. It turned out that the kinetic energy of the electrons that were expelled was related to the speed at which the light was coming from. It didn't matter how bright the light was coming in. When the frequency of the light is less than a certain value, there is no current, no matter how bright the light is. All of these conclusions are against the wave theory.

Generation of Electromagnetic Radiation

Electromagnetic radiation is generated anytime the velocity of a charged particle, such as an electron, changes—that is, when it is accelerated or decelerated. The energy in the electromagnetic radiation originates with the charged particle and is hence dissipated by it. The oscillating charge or current in a radio antenna is a classic example of this phenomenon. One way to achieve a specific frequency using a radio transmitter's antenna is to embed it into an electric resonance circuit. An electromagnetic wave can be picked up using a tuner with an oscillating electric circuit set to the same frequency as the antenna. An oscillating motion of charge in the receiving antenna is the result of the electromagnetic wave. Generally, a system that generates electromagnetic radiation of a certain frequency may absorb radiation of the same frequency in the same way. These human-made transmitters and receivers become unworkable as the wavelength of the electromagnetic wave decreases and are therefore unusable in the millimeter range. At even shorter wavelengths, such as those of X-rays, the oscillating charges are caused by moving charges in molecules and atoms. Both systems and processes that produce electromagnetic radiation can be divided into two groups: (1) those whose output is spread throughout a wide range of frequencies, and (2) those whose output is limited to a single frequency. There are two types of radio transmitters: those tuned to specific frequencies and those tuned to the Sun's continuous spectrum.

The Greenhouse Effect of the Atmosphere

It is not just the Sun's electromagnetic radiation that affects the Earth's temperature but also its atmosphere. When it comes to absorbing and emitting electromagnetic radiation, each substance has its own unique spectrum of frequencies. Depending on how the substance's internal energies are distributed, these zones of transparency and opaqueness can be seen or hidden. Unlike the glass panes of a greenhouse, Earth's atmosphere allows sunlight to reach and warm the planet. Generally, it blocks the infrared radiation released by the heated terrestrial surface from escaping into space. There is less atmospheric absorption in higher altitude zones to compensate for the thinned atmosphere above Earth's surface. Only one ten-millionth of the amount of atmosphere is present at the height of 100 kilometers (62 miles). The ionosphere, a layer of the atmosphere in which atoms and molecules in the atmosphere are ionized by UV radiation from the Sun, is responsible for absorption below 10 million hertz (107 Hz). The absorption in the infrared range is a result of molecular vibrations and rotations. The electronic excitations in atoms and molecules cause absorption in the ultraviolet and X-ray areas. Temperature fluctuations between day and night on Earth would be much worse if water vapor and carbon dioxide (CO2), the principal infrared-absorbing species in the atmosphere, and other industrial pollutants weren't present. If this were to happen, Earth would turn into a frozen world similar to Mars, with an average temperature of 200 K (73 °C or 100 °F). Carbon dioxide and other gaseous pollutants affect the Earth's temperature and climate when released and accumulated in the atmosphere.

Electromagnetic Radiation

In classical physics, electromagnetic radiation is defined as the movement of energy through free space or a material medium at the speed of light in the form of electric and magnetic fields, which combine to generate electromagnetic waves such as gamma rays, visible light, and radio waves. There is a synchronization of electric and magnetic fields in the electromagnetic waves. The speed of light c is the same as the speed of electromagnetic waves. Perpendicular to the fields, a wave propagates in isotropic and homogeneous mediums. As a transverse wave, these fields are perpendicular to one another. When electromagnetic waves are emitted from a single point source, the wavefront has the appearance of a sphere. Electromagnetic waves are classified by their frequency and wavelength in the electromagnetic spectrum. Electromagnetic waves of different frequencies have distinct names based on where they originate and how they affect the environment.

According to contemporary quantum theory, electromagnetic radiation is the flow of photons (also known as light quanta) through space. Photons are energy particles that travel at the speed of light at all times. The sign h stands for Planck's constant, and the value of v is equal to the frequency of an electromagnetic wave in classical theory. All photons with the same energy h are similar, and their numerical density is proportional to the radiation's intensity. When electromagnetic radiation interacts with charged particles in atoms, molecules, and bigger objects of matter, it encompasses a set of characteristics. These characteristics, the methods of generating and monitoring electromagnetic radiation, the way it happens naturally, and its technological applications are all dependent on its frequency.

Occurrence and Importance

Electromagnetic radiation accounts for about 0.01% of the total mass/energy of the universe. It permeates many aspects of human life, and current communications technology and health care rely heavily on one or more of its manifestations. Most species' eyes, including humans, are used to being sensitive to and thus see the most plentiful component of the Sun's electromagnetic radiation—light, which constitutes the visible portion of the Sun's broad spectrum of frequencies. Additionally, green plants exhibit high responsiveness to the high intensity of solar electromagnetic radiation, which is absorbed by a chemical called chlorophyll, required for photosynthesis-based plant growth. Almost all of the fuels used in the 21st century, including gas, oil, and coal, are stored forms of energy received from the sun centuries ago as electromagnetic radiation.

Properties

Electromagnetism is a physical phenomenon that exemplifies the electrodynamics theory. The electric and magnetic fields operate on the superposition principle. A time-varying electric or magnetic field, or a field generated by any particular particle, adds to the fields already present in the area from other sources. The magnetic and electric fields are vector fields; hence, these two fields' combination follows the same rules. A constructive or destructive interference pattern is formed when two or more coherent light waves interact. The resulting irradiation is different from the sum of the individual overlapping light waves' constituent irradiances. When the electromagnetic field moves through static and magnetic fields in a medium that moves in a straight line, like a vacuum, they don't change. In the case of non-linear media, there is a chance for some interaction. Light and static magnetic or electric fields interact in media such as certain crystals through the Faraday and Kerr effects.

When a light wave refracts, it does so via two distinct mediums of varying densities. The light wave's speed and direction change as a result of this. Snell's law states that the ratio of the two media's refractive indices determines how much the path changes. Compound wavelengths make up most of the light we see in the daylight. When light travels through a prism, it splits into a range of colors that can be seen with the naked eye. As a result, the wavelength of the light traveling through the prism affects its refractive index. As a result, the components of sunlight undergo varying degrees of bending, resulting in a spectrum.

Wave Model

As a homogeneous, isotropic medium, electromagnetic radiation travels in transverse waves. A transverse amplitude wave shows an energy transfer path perpendicular to the wave's oscillations. The electric and magnetic fields are synchronized. They both reach their highest and lowest peaks at the same time. There is a widespread belief that the two fields are not in sync. That's because one feeds off the other in a mutually exclusive manner. The electric and magnetic fields can have a phase difference if the fields are sinusoidal functions. Near-field antennas are affected by this. Far-field electromagnetic radiation has a time-space relationship, which means that the time difference between one type of field and the other is proportionate. This necessitates that both fields be in sync. The crests and troughs of a monochromatic wave, which refers to an electromagnetic wave with a single frequency, are cyclical in nature. The wavelength is defined as the distance between two successive troughs or crests. The wavelengths of electromagnetic waves are determined by their size. The frequency has an inverse relationship with the electromagnetic wave's wavelength.

Particle Model

The black body radiation was shown to be incompatible with the wave model of light. Max Planck, a scientist, proposed the hypothesis of black-body radiation in 1900. This theory provided an explanation for the observed spectrum. The hypothesis is predicated on the assumption that light is emitted in discrete packets of energy. These energy bundles are quanta of energy. Albert Einstein linked light quanta to original particles in 1905. For this reason, the light particle was referred to as a photon, a nod to electrons and protons at the time. The photon's energy is proportional to the wave's frequency. The photoelectric effect was a strange phenomenon that light's wave nature couldn't explain. This experiment convinced Einstein that light was made up of particles. When a specific frequency of light strikes a metal surface, electrons are expelled from it. When a voltage is placed across, this results in the flow of an electric current. It turned out that the kinetic energy of the electrons that were expelled was related to the speed at which the light was coming from. It didn't matter how bright the light was coming in. When the frequency of the light is less than a certain value, there is no current, no matter how bright the light is. All of these conclusions are against the wave theory.

Generation of Electromagnetic Radiation

Electromagnetic radiation is generated anytime the velocity of a charged particle, such as an electron, changes—that is, when it is accelerated or decelerated. The energy in the electromagnetic radiation originates with the charged particle and is hence dissipated by it. The oscillating charge or current in a radio antenna is a classic example of this phenomenon. One way to achieve a specific frequency using a radio transmitter's antenna is to embed it into an electric resonance circuit. An electromagnetic wave can be picked up using a tuner with an oscillating electric circuit set to the same frequency as the antenna. An oscillating motion of charge in the receiving antenna is the result of the electromagnetic wave. Generally, a system that generates electromagnetic radiation of a certain frequency may absorb radiation of the same frequency in the same way. These human-made transmitters and receivers become unworkable as the wavelength of the electromagnetic wave decreases and are therefore unusable in the millimeter range. At even shorter wavelengths, such as those of X-rays, the oscillating charges are caused by moving charges in molecules and atoms. Both systems and processes that produce electromagnetic radiation can be divided into two groups: (1) those whose output is spread throughout a wide range of frequencies, and (2) those whose output is limited to a single frequency. There are two types of radio transmitters: those tuned to specific frequencies and those tuned to the Sun's continuous spectrum.

The Greenhouse Effect of the Atmosphere

It is not just the Sun's electromagnetic radiation that affects the Earth's temperature but also its atmosphere. When it comes to absorbing and emitting electromagnetic radiation, each substance has its own unique spectrum of frequencies. Depending on how the substance's internal energies are distributed, these zones of transparency and opaqueness can be seen or hidden. Unlike the glass panes of a greenhouse, Earth's atmosphere allows sunlight to reach and warm the planet. Generally, it blocks the infrared radiation released by the heated terrestrial surface from escaping into space. There is less atmospheric absorption in higher altitude zones to compensate for the thinned atmosphere above Earth's surface. Only one ten-millionth of the amount of atmosphere is present at the height of 100 kilometers (62 miles). The ionosphere, a layer of the atmosphere in which atoms and molecules in the atmosphere are ionized by UV radiation from the Sun, is responsible for absorption below 10 million hertz (107 Hz). The absorption in the infrared range is a result of molecular vibrations and rotations. The electronic excitations in atoms and molecules cause absorption in the ultraviolet and X-ray areas. Temperature fluctuations between day and night on Earth would be much worse if water vapor and carbon dioxide (CO2), the principal infrared-absorbing species in the atmosphere, and other industrial pollutants weren't present. If this were to happen, Earth would turn into a frozen world similar to Mars, with an average temperature of 200 K (73 °C or 100 °F). Carbon dioxide and other gaseous pollutants affect the Earth's temperature and climate when released and accumulated in the atmosphere.