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- The various portions bear different names based on differences in behaviour in the emission, transmission, and absorption of the corresponding waves and also based on their different practical applications.
www.britannica.com/science/electromagnetic-spectrum
The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Mar 27, 2021 · The energy waves obtained by shooting electrons in micro ovens are also called micro waves, for which the speed in vacuum is less than the speed of light in vacuum, in view of de Broglie law. Since micro waves of micro ovens have less speed, my first question is the following:
- Overview
- The electromagnetic spectrum
- Generation of electromagnetic radiation
The brief account of familiar phenomena given above surveyed electromagnetic radiation from low frequencies of ν (radio waves) to exceedingly high values of ν (gamma rays). Going from the ν values of radio waves to those of visible light is like comparing the thickness of this page with the distance of Earth from the Sun, which represents an increase by a factor of a million billion. Similarly, going from the ν values of visible light to the very much larger ones of gamma rays represents another increase in frequency by a factor of a million billion. This extremely large range of ν values, called the electromagnetic spectrum, is shown in Figure 1, together with the common names used for its various parts, or regions.
The number ν is shared by both the classical and the modern interpretation of electromagnetic radiation. In classical language, ν is the frequency of the temporal changes in an electromagnetic wave. The frequency of a wave is related to its speed c and wavelength λ in the following way. If 10 complete waves pass by in one second, one observes 10 wriggles, and one says that the frequency of such a wave is ν = 10 cycles per second (10 hertz [Hz]). If the wavelength of the wave is, say, λ = 3 cm, then it is clear that a wave train 30 cm long has passed in that one second to produce the 10 wriggles that were observed. Thus, the speed of the wave is 30 cm per second, and one notes that in general the speed is c = λν. The speed of electromagnetic radiation of all kinds is the same universal constant that is defined to be exactly c = 299,792,458 metres per second (186,282 miles per second). The wavelengths of the classical electromagnetic waves in free space calculated from c = λν are also shown on the spectrum in Figure 1, as is the energy hν of modern-day photons. Commonly used as the unit of energy is the electron volt (eV), which is the energy that can be given to an electron by a one-volt battery. It is clear that the range of wavelengths λ and of photon energies hν are equally as large as the spectrum of ν values.
Because the wavelengths and energy quanta hν of electromagnetic radiation of the various parts of the spectrum are so different in magnitude, the sources of the radiations, the interactions with matter, and the detectors employed are correspondingly different. This is why the same electromagnetic radiation is called by different names in various regions of the spectrum.
In spite of these obvious differences of scale, all forms of electromagnetic radiation obey certain general rules that are well understood and that allow one to calculate with very high precision their properties and interactions with charged particles in atoms, molecules, and large objects. Electromagnetic radiation is, classically speaking, a wave of electric and magnetic fields propagating at the speed of light c through empty space. In this wave the electric and magnetic fields change their magnitude and direction each second. This rate of change is the frequency ν measured in cycles per second—namely, in hertz. The electric and magnetic fields are always perpendicular to each other and at right angles to the direction of propagation, as shown in Figure 2. There is as much energy carried by the electric component of the wave as by the magnetic component, and the energy is proportional to the square of the field strength.
The brief account of familiar phenomena given above surveyed electromagnetic radiation from low frequencies of ν (radio waves) to exceedingly high values of ν (gamma rays). Going from the ν values of radio waves to those of visible light is like comparing the thickness of this page with the distance of Earth from the Sun, which represents an increase by a factor of a million billion. Similarly, going from the ν values of visible light to the very much larger ones of gamma rays represents another increase in frequency by a factor of a million billion. This extremely large range of ν values, called the electromagnetic spectrum, is shown in Figure 1, together with the common names used for its various parts, or regions.
The number ν is shared by both the classical and the modern interpretation of electromagnetic radiation. In classical language, ν is the frequency of the temporal changes in an electromagnetic wave. The frequency of a wave is related to its speed c and wavelength λ in the following way. If 10 complete waves pass by in one second, one observes 10 wriggles, and one says that the frequency of such a wave is ν = 10 cycles per second (10 hertz [Hz]). If the wavelength of the wave is, say, λ = 3 cm, then it is clear that a wave train 30 cm long has passed in that one second to produce the 10 wriggles that were observed. Thus, the speed of the wave is 30 cm per second, and one notes that in general the speed is c = λν. The speed of electromagnetic radiation of all kinds is the same universal constant that is defined to be exactly c = 299,792,458 metres per second (186,282 miles per second). The wavelengths of the classical electromagnetic waves in free space calculated from c = λν are also shown on the spectrum in Figure 1, as is the energy hν of modern-day photons. Commonly used as the unit of energy is the electron volt (eV), which is the energy that can be given to an electron by a one-volt battery. It is clear that the range of wavelengths λ and of photon energies hν are equally as large as the spectrum of ν values.
Because the wavelengths and energy quanta hν of electromagnetic radiation of the various parts of the spectrum are so different in magnitude, the sources of the radiations, the interactions with matter, and the detectors employed are correspondingly different. This is why the same electromagnetic radiation is called by different names in various regions of the spectrum.
In spite of these obvious differences of scale, all forms of electromagnetic radiation obey certain general rules that are well understood and that allow one to calculate with very high precision their properties and interactions with charged particles in atoms, molecules, and large objects. Electromagnetic radiation is, classically speaking, a wave of electric and magnetic fields propagating at the speed of light c through empty space. In this wave the electric and magnetic fields change their magnitude and direction each second. This rate of change is the frequency ν measured in cycles per second—namely, in hertz. The electric and magnetic fields are always perpendicular to each other and at right angles to the direction of propagation, as shown in Figure 2. There is as much energy carried by the electric component of the wave as by the magnetic component, and the energy is proportional to the square of the field strength.
Electromagnetic radiation is produced whenever a charged particle, such as an electron, changes its velocity—i.e., whenever it is accelerated or decelerated. The energy of the electromagnetic radiation thus produced comes from the charged particle and is therefore lost by it. A common example of this phenomenon is the oscillating charge or current in a radio antenna. The antenna of a radio transmitter is part of an electric resonance circuit in which the charge is made to oscillate at a desired frequency. An electromagnetic wave so generated can be received by a similar antenna connected to an oscillating electric circuit in the tuner that is tuned to that same frequency. The electromagnetic wave in turn produces an oscillating motion of charge in the receiving antenna. In general, one can say that any system which emits electromagnetic radiation of a given frequency can absorb radiation of the same frequency.
Such human-made transmitters and receivers become smaller with decreasing wavelength of the electromagnetic wave and prove impractical in the millimetre range. At even shorter wavelengths down to the wavelengths of X-rays, which are one million times smaller, the oscillating charges arise from moving charges in molecules and atoms.
Aug 29, 2023 · Describing Electromagnetic Waves. Scientists describe electromagnetic waves using three primary properties: frequency (f), wavelength (λ), and photon energy (E). These properties relate to one another through the following formulas: c=f×λ Where c is the speed of light in a vacuum (3×10 8 m/s) E=h×f
Ultraviolet light gets its name because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. Most UV is non- ionizing radiation, though UV with higher energies (10-120 nm) is ionizing.
Explain why the higher the frequency, the shorter the wavelength of an electromagnetic wave. Draw a simplified electromagnetic spectrum, indicating the relative positions, frequencies, and spacing of the different types of radiation bands.
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Oct 21, 2024 · electromagnetic spectrum, the entire distribution of electromagnetic radiation according to frequency or wavelength. Although all electromagnetic waves travel at the speed of light in a vacuum, they do so at a wide range of frequencies, wavelengths, and photon energies.
