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  2. Hertz - Wikipedia

    en.wikipedia.org/wiki/Hertz

    The hertz is defined as one per second for periodic events. The International Committee for Weights and Measures defined the second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom" [3] [4] and then adds: "It follows that the hyperfine splitting in the ground state of the ...

  3. Frequency - Wikipedia

    en.wikipedia.org/wiki/Frequency

    A pendulum with a period of 2.8 s and a frequency of 0.36 Hz. For cyclical phenomena such as oscillations, waves, or for examples of simple harmonic motion, the term frequency is defined as the number of cycles or repetitions per unit of time.

  4. Energy conversion efficiency - Wikipedia

    en.wikipedia.org/wiki/Energy_conversion_efficiency

    Energy converter is an example of an energy transformation. For example, a light bulb falls into the categories energy converter. η = P o u t P i n {\displaystyle \eta ={\frac {P_{\mathrm {out} }}{P_{\mathrm {in} }}}} Even though the definition includes the notion of usefulness, efficiency is considered a technical or physical term.

  5. Clock rate - Wikipedia

    en.wikipedia.org/wiki/Clock_rate

    The clock rate of the first generation of computers was measured in hertz or kilohertz (kHz), the first personal computers from the 1970s through the 1980s had clock rates measured in megahertz (MHz).

  6. Conversion of units - Wikipedia

    en.wikipedia.org/wiki/Conversion_of_units

    3.1 Calculate the factor. 3.2 Calculate the ... 1 mile = 5280 feet and 1 hour = 3600 seconds; Next use the above equations to construct a fraction that has a value of ...

  7. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    Subdivisions of the day include the hour (1/24 of a day), which is further subdivided into minutes and seconds. The second is the international standard unit (SI unit) for science. Celestial sphere-based: as in sidereal time, where the apparent movement of the stars and constellations across the sky is used to calculate the length of a year.

  8. Electromagnetic wave equation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_wave_equation

    The electromagnetic wave equation is a second-order partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum. It is a three-dimensional form of the wave equation. The homogeneous form of the equation, written in terms of either the electric field E or the magnetic field B, takes the form:

  9. Light - Wikipedia

    en.wikipedia.org/wiki/Light

    Another example is incandescent light bulbs, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in flames , but these also emit most of their radiation in the infrared and only a fraction in the visible spectrum.