Is no stranger to direct current (dc) and alternating current (ac), such as dry cell output current to direct current (dc), and the grid is an alternating current. You ever thought about the difference between dc and ac, its can through what way can the direct current (dc) and alternating current (ac) detected?
Direct current (dc) than invented by alternating current (ac), so what kind of electric current is called dc? Don't change over time as long as the direction of current is called a straightFlow, such as shown below current waveform, found in current size do periodic changes over time, although no change of direction, but its size has changed, called the dc pulse dc.If current size and direction of all the current does not change over time, is called a constant current.
Alternating current (ac) than direct current (dc) invented by night, but it has been invented, and at the time of the era is gaining recognition and has been widely promoted. Because at that time haven't developed the power electronic technology, direct current (dc) there is no way to step up, causing great energy loss during transmission, is not the economy. But its size and the direction for alternating current (ac) do periodic changes over time, alternating current (ac) at the same time can make use of electromagnetic induction principle through step-up transformer, from in the premise of a certain power transmission can reduce the energy loss in the transmission lines. The mains voltage waveform as the sinusoidal alternating current waveform, frequency 50 hz.
By common electrical appliance test pen can be detected is an alternating current or direct current. If an alternating current through the test pen, alternating current (ac) can make the neon of two alternate emission electron, alternates for alternating current (ac) its positive and negative polarity is changed, so the neon both very bright. For direct current (dc) is a highly launch electronic neon, because it has a fixed polarity for direct current (dc), so only a very bright neon. Using this method to determine dc and ac has obvious distinguish.
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