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  2. Natural sounds - Wikipedia

    en.wikipedia.org/wiki/Natural_sounds

    Natural sounds are any sounds produced by non-human organisms as well as those generated by natural, non-biological sources within their normal soundscapes. It is a category whose definition is open for discussion. Natural sounds create an acoustic space . The definition of the soundscape can be broken down into three components: the geophony ...

  3. Infrasound - Wikipedia

    en.wikipedia.org/wiki/Infrasound

    Infrasound is characterized by an ability to get around obstacles with little dissipation. In music, acoustic waveguide methods, such as a large pipe organ or, for reproduction, exotic loudspeaker designs such as transmission line, rotary woofer, or traditional subwoofer designs can produce low-frequency sounds, including near-infrasound.

  4. Mercury (element) - Wikipedia

    en.wikipedia.org/wiki/Mercury_(element)

    Mercury is a chemical element; it has symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( / haɪˈdrɑːrdʒərəm / hy-DRAR-jər-əm) from the Greek words hydor (water) and argyros (silver), from which its chemical symbol is derived. [ 8]

  5. Spectrum (physical sciences) - Wikipedia

    en.wikipedia.org/wiki/Spectrum_(physical_sciences)

    A source of sound can have many different frequencies mixed. A musical tone's timbre is characterized by its harmonic spectrum. Sound in our environment that we refer to as noise includes many different frequencies. When a sound signal contains a mixture of all audible frequencies, distributed equally over the audio spectrum, it is called white ...

  6. Molecular vibration - Wikipedia

    en.wikipedia.org/wiki/Molecular_vibration

    Molecular vibration. A molecular vibration is a periodic motion of the atoms of a molecule relative to each other, such that the center of mass of the molecule remains unchanged. The typical vibrational frequencies range from less than 10 13 Hz to approximately 10 14 Hz, corresponding to wavenumbers of approximately 300 to 3000 cm −1 and ...

  7. Bismuth - Wikipedia

    en.wikipedia.org/wiki/Bismuth

    Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs naturally, and its sulfide and oxide forms are important commercial ores.

  8. Pollution - Wikipedia

    en.wikipedia.org/wiki/Pollution

    Pollution is the introduction of contaminants into the natural environment that cause adverse change. [ 1] Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring ...

  9. Matter - Wikipedia

    en.wikipedia.org/wiki/Matter

    Matter. Hydrogen in its plasma state is the most abundant ordinary matter in the universe. In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. [ 1] All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles ...