what do we mean by negative amplitude,what does it mean physically?

Question

radar · Answer

If you are referring to alternating current the negative portion is flowing in the opposite direction that it was during the positive alternation assuming no phase difference between voltage and current.  It means the source voltage has switched polarity and the terminals are now opposite what it was during the positive portion.

anonymous · Answer

I don't really know! but I have an idea and that is that it is most likely just as it says, it is the negative amplitude of the mirror positive amplitude depending on the medians location as if the median (centre) moves along +x than P(-x) will move along x in a + direction  and +x will move in a + direction if in fact +x and -x are in fixed positions to each other.
 This could probably be made into a perpendicular 360 degree symetry along the x median and the median may also be affected by a magnetic force or resonace and so on...
?MAYBE?

luke · Answer

sin waves oscilate on the vertical axis while continuing horizontally on the x axis. this gives an apparent median from which the amplitude can be measured and the amplitude describes the distance both to a crest and to a trough. however when looking from the median to a trough in the wave, the amplitude is not negative, it is positive.

anonymous · Answer

a ggod way of thinking about it is by imagining water waves. firstly imagine flat, still water. this on a graph would be your y=0 line. if you now make a wave (nothing too splashy) at first a crest will form above that line (the top of theat crest will be the positive amplitude) behinde it however will be a dip (because the water that was there has been moved into the crest ; it works a bit like a vacuum) this dip will be below the y=0 line. this will therefore have negative amplitude. so negative amplitude really means that the wave level is below the rest level of the medium.

anonymous · Answer

I appreciate your response but sorry to say that the answers look naive, everyone should know these answers or can easily look wikipedia for such stuff... I am looking for something hidden there, (I mean physics meaning in case of current).