<P> The term DC is used to refer to power systems that use only one polarity of voltage or current , and to refer to the constant , zero - frequency , or slowly varying local mean value of a voltage or current . For example , the voltage across a DC voltage source is constant as is the current through a DC current source . The DC solution of an electric circuit is the solution where all voltages and currents are constant . It can be shown that any stationary voltage or current waveform can be decomposed into a sum of a DC component and a zero - mean time - varying component ; the DC component is defined to be the expected value , or the average value of the voltage or current over all time . </P>
<P> The term DC is used to refer to power systems that use only one polarity of voltage or current , and to refer to the constant , zero - frequency , or slowly varying local mean value of a voltage or current . For example , the voltage across a DC voltage source is constant as is the current through a DC current source . The DC solution of an electric circuit is the solution where all voltages and currents are constant . It can be shown that any stationary voltage or current waveform can be decomposed into a sum of a DC component and a zero - mean time - varying component ; the DC component is defined to be the expected value , or the average value of the voltage or current over all time . </P>
what is the frequency of a dc voltage
what is the frequency of a dc voltage
zero
zero