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  2. File:Wave packet propagation (phase faster than group ...

    en.wikipedia.org/wiki/File:Wave_packet...

    Original file (816 × 408 pixels, file size: 939 KB, MIME type: image/gif, looped, 120 frames, 4.0 s) This is a file from the Wikimedia Commons . Information from its description page there is shown below.

  3. Electromagnetic radiation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_radiation

    However, at energies too low to excite water vapor, the atmosphere becomes transparent again, allowing free transmission of most microwave and radio waves. [ 51 ] Finally, at radio wavelengths longer than 10 m or so (about 30 MHz), the air in the lower atmosphere remains transparent to radio, but plasma in certain layers of the ionosphere ...

  4. Electromagnetic absorption by water - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_absorption...

    [19] [20] [15] The regions between these bands can be used in near-infrared spectroscopy to measure the spectra of aqueous solutions, with the advantage that glass is transparent in this region, so glass cuvettes can be used. The absorption intensity is weaker than for the fundamental vibrations, but this is not important as longer path-length ...

  5. Wave - Wikipedia

    en.wikipedia.org/wiki/Wave

    Electromagnetic waves can travel through a vacuum and through some dielectric media (at wavelengths where they are considered transparent). Electromagnetic waves, as determined by their frequencies (or wavelengths), have more specific designations including radio waves, infrared radiation, terahertz waves, visible light, ultraviolet radiation ...

  6. Category:Featured animations - Wikipedia

    en.wikipedia.org/wiki/Category:Featured_animations

    Shallow water waves.gif 491 × 258; 7.02 MB. Sieve of Eratosthenes animation.gif 445 × 369; 154 KB. Snells law wavefronts.gif 225 × 227; 65 KB.

  7. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    Earth's atmosphere is mainly transparent to radio waves, except for layers of charged particles in the ionosphere which can reflect certain frequencies. Radio waves are extremely widely used to transmit information across distances in radio communication systems such as radio broadcasting , television , two way radios , mobile phones ...

  8. Transparency and translucency - Wikipedia

    en.wikipedia.org/wiki/Transparency_and_translucency

    A transparency of 50 percent is enough to make an animal invisible to a predator such as cod at a depth of 650 metres (2,130 ft); better transparency is required for invisibility in shallower water, where the light is brighter and predators can see better. For example, a cod can see prey that are 98 percent transparent in optimal lighting in ...

  9. Photoelectric effect - Wikipedia

    en.wikipedia.org/wiki/Photoelectric_effect

    In 1887, Heinrich Hertz observed the photoelectric effect [25] and reported on the production and reception [26] of electromagnetic waves. [27] The receiver in his apparatus consisted of a coil with a spark gap, where a spark would be seen upon detection of electromagnetic waves. He placed the apparatus in a darkened box to see the spark better.