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  2. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    Wavelengths of electromagnetic radiation, whatever medium they are traveling through, are usually quoted in terms of the vacuum wavelength, although this is not always explicitly stated. Generally, electromagnetic radiation is classified by wavelength into radio wave, microwave, infrared, visible light, ultraviolet, X-rays and gamma rays. The ...

  3. Electromagnetic radiation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_radiation

    Electromagnetic waves of different frequency are called by different names since they have different sources and effects on matter. In order of increasing frequency and decreasing wavelength, the electromagnetic spectrum includes: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. [3] [4]

  4. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    Visible wavelengths pass largely unattenuated through the Earth's atmosphere via the "optical window" region of the electromagnetic spectrum. An example of this phenomenon is when clean air scatters blue light more than red light, and so the midday sky appears blue (apart from the area around the Sun which appears white because the light is not ...

  5. Redshift - Wikipedia

    en.wikipedia.org/wiki/Redshift

    In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light).The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift, or negative redshift.

  6. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    10 cm = 1.0 dm – wavelength of the highest UHF radio frequency, 3 GHz; 12 cm = 1.2 dm – wavelength of the 2.45 GHz ISM radio band; 21 cm = 2.1 dm – wavelength of the 1.4 GHz hydrogen emission line, a hyperfine transition of the hydrogen atom; 100 cm = 10 dm – wavelength of the lowest UHF radio frequency, 300 MHz

  7. High frequency - Wikipedia

    en.wikipedia.org/wiki/High_frequency

    HF's position in the electromagnetic spectrum.. High frequency (HF) is the ITU designation [1] [2] for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters).

  8. Spectral slope - Wikipedia

    en.wikipedia.org/wiki/Spectral_slope

    In astrophysics and planetary science, spectral slope, also called spectral gradient, is a measure of dependence of the reflectance on the wavelength. In digital signal processing, it is a measure of how quickly the spectrum of an audio sound tails off towards the high frequencies, calculated using a linear regression. [1]

  9. Wien's displacement law - Wikipedia

    en.wikipedia.org/wiki/Wien's_displacement_law

    Formally, the wavelength version of Wien's displacement law states that the spectral radiance of black-body radiation per unit wavelength, peaks at the wavelength given by: = where T is the absolute temperature and b is a constant of proportionality called Wien's displacement constant, equal to 2.897 771 955... × 10 −3 m⋅K, [1] [2] or b ...