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  2. Direct current - Wikipedia

    en.wikipedia.org/wiki/Direct_current

    The term DC is used to refer to power systems that use only one electrical polarity of voltage or current, and to refer to the constant, zero-frequency, or slowly varying local mean value of a voltage or current. [9] For example, the voltage across a DC voltage source is constant as is the current through a direct current source.

  3. Alternating current - Wikipedia

    en.wikipedia.org/wiki/Alternating_current

    The abbreviations AC and DC are often used to mean simply alternating and direct, respectively, as when they modify current or voltage. [ 1 ] [ 2 ] The usual waveform of alternating current in most electric power circuits is a sine wave , whose positive half-period corresponds with positive direction of the current and vice versa (the full ...

  4. Glossary of electrical and electronics engineering - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_electrical_and...

    The root mean square value of a waveform is the DC value that corresponds to equivalent heating value. rotary converter An electric machine that converts electric power between two forms, say, AC and DC or single-phase and three phase, or between two different frequencies of AC (the latter two can be performed by the same machine). rotary encoder

  5. Volt - Wikipedia

    en.wikipedia.org/wiki/Volt

    They made the volt equal to 10 8 cgs units of voltage, the cgs system at the time being the customary system of units in science. They chose such a ratio because the cgs unit of voltage is inconveniently small and one volt in this definition is approximately the emf of a Daniell cell , the standard source of voltage in the telegraph systems of ...

  6. List of vacuum tubes - Wikipedia

    en.wikipedia.org/wiki/List_of_vacuum_tubes

    All have 1.25 volt DC filaments and directly heated cathodes. Some specify which end of the filament is to be powered by the positive side of the filament power supply (usually a battery). All have glass bodies that measure from 0.285 to 0.400 inches (7.2 to 10.2 millimetres) wide, and from 1.25 to 2.00 inches (32 to 51 millimetres) in overall ...

  7. Multimeter - Wikipedia

    en.wikipedia.org/wiki/Multimeter

    The digital display value as opposed to an analog display is subjectively more difficult to read. This continuous tracking feature becomes important when testing capacitors or coils, for example. A properly functioning capacitor should allow current to flow when voltage is applied, then the current slowly decreases to zero and this "signature ...

  8. Science fair - Wikipedia

    en.wikipedia.org/wiki/Science_fair

    A science fair or engineering fair is an event hosted by a school that offers students the opportunity to experience the practices of science and engineering for themselves. In the United States, the Next Generation Science Standards makes experiencing the practices of science and engineering one of the three pillars of science education.

  9. Orders of magnitude (voltage) - Wikipedia

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

    A common voltage for medium-size electric lanterns. [19] A voltage for older electric systems of automobiles. Deca-10 1: 12 V Typical car battery [20] Hecto-10 2: 100–240 V Domestic wall socket voltage [21] 600 V Electric eel sends this voltage in an average attack 630 V London Underground railway tracks Kilo-10 3: 2450 V