Why is the characteristic frequncy applicable only to AC voltage?

Question

i am student

Answer 1

As the name says, AC alternates, the magnitude of voltage keeps revolving from 0 to 360 degrees. more technically I can say, it starts from 0, and reaches its positive high at 90 degrees and reaches 0 at 180 degrees and goes to its negative peak at 270 degrees and goes to 0 again in 360 degrees. this point will be the 0 degree for the next cycle. Normally this happens in a rate depending upon the frequency of the Supply. for eg, in India it is 50Hz, that is in 1 second, the above said cycle will happen for 50 times. In the US, it is 60 Hz. (that incandescent bulb in your house glows and goes off 50/60 times in a second.. belive me :) )

DC, is direct current. in DC we have terminals, +ve and -ve, which are fixed. the positive peak will always be in positive peak. and negative peak will be in negative always. so, no frequency comes into picture.

Answer 2

Characteristic frequency is not applicable only to AC voltages, since there are many naturally-occurring systems that exhibit natural oscillations.

The term 'characteristic frequency' is also often called the 'natural frequency', since this is a frequency at which a 2nd-order (or higher) system will naturally oscillate.  Think:  ringing a bell, or plucking a violin string.

At zero frequency, which is DC, oscillations can't exist, so the input produces only a fixed deviation.  Think:  dented bell or moving the violin string one direction and holding it there.

We do operate our power systems at nearly-fixed select frequencies, but these are not the characteristic or natural frequencies of the system.  It would be catastrophic if we tried to operate the grid at one of its characteristic frequencies

Answer 3

AC stands for Alternating Current. Means it alternates (its direction) unlike DC (direct current). Constant alternating behavior (vibration) of charged particles create a sine wave. Sine wave is a constant wave with a frequency among other general characteristics of all wave forms. And of course, frequency is  measured in Hertz (Hz - or Cycles per Sec). Thats why you notice a certain Hz value with Voltage description behind your most electrical appliances. DC does not change direction and hence does not create a vibration of its particles and therefore no constant sine wave to associate itself with a value of frequency.  

Answer 4

AC current alternates its direction continuously. The frequency gives the number of times the current changes its direction per second (if it is measured in Hz).Since DC doesn't changes it's direction therefore it's frequency is always zero and.