Triple N Posted March 2, 2011 Share Posted March 2, 2011 Can Negative DC voltage be measured? If yes then how and what will be the range of its values. Link to comment Share on other sites More sharing options...
Schrödinger's hat Posted March 2, 2011 Share Posted March 2, 2011 Can Negative DC voltage be measured? If yes then how and what will be the range of its values. As I was trying to explain in the chat before you wandered off. Potential difference can be positive or negative. The range is any number from negative infinity to infinity. You measure them the same way you measure any voltage difference. If your volt meter doesn't measure negative voltage, swap the leads. If you are too lazy to take the time to try and understand things properly then I can't help you any further. I just realized you could be having trouble with IRC and not receiving all the messages. If that is the case then I apologise for getting cranky, and you don't deserve it.Perhaps you can explain what you are trying to do in more detail? Link to comment Share on other sites More sharing options...
TonyMcC Posted March 2, 2011 Share Posted March 2, 2011 Can also be measured on a cathode ray oscilloscope set to a dc range. The trace will lower itself instead of lifting. Link to comment Share on other sites More sharing options...
swansont Posted March 2, 2011 Share Posted March 2, 2011 Positive and negative are arbitrary choices. It depends on what point you define as being zero. Link to comment Share on other sites More sharing options...
TonyMcC Posted March 2, 2011 Share Posted March 2, 2011 Positive and negative are arbitrary choices. It depends on what point you define as being zero. True - but usually earth is regarded as zero, e.g to be precise one might ask "how do I measure a voltage which is negative with respect to (w.r.t.) earth?" Link to comment Share on other sites More sharing options...
lemur Posted March 2, 2011 Share Posted March 2, 2011 (edited) True - but usually earth is regarded as zero, e.g to be precise one might ask "how do I measure a voltage which is negative with respect to (w.r.t.) earth?" The first thing I thought of when reading this was the possibility of a lighting bolt from the Earth to the moon or some other point in outer space. But then I wondered if energy would actually travel through a vacuum as electricity, and I don't think it can without some form of conductor or ions coming in contact with each other. So, doesn't electric potential have to get released as radiation if their is too much insulation for it to conduct elsewhere? Or can charge build up indefinitely within a vacuum without resulting in photon emissions? Sorry if this is too divergent from the OP. Maybe a more specific related question is whether negative voltage is a comparable concept to negative temperature where temperature is measured in C or some other scale whose zero-point is absolute zero? Edited March 2, 2011 by lemur Link to comment Share on other sites More sharing options...
swansont Posted March 2, 2011 Share Posted March 2, 2011 True - but usually earth is regarded as zero, e.g to be precise one might ask "how do I measure a voltage which is negative with respect to (w.r.t.) earth?" Doesn't matter. A capacitor with the (nominally) positive plate at ground. Or two capacitors in series, and the point in between them is ground. The negatively charged plate will have a negative voltage wrt ground. Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted March 2, 2011 Share Posted March 2, 2011 The first thing I thought of when reading this was the possibility of a lighting bolt from the Earth to the moon or some other point in outer space. But then I wondered if energy would actually travel through a vacuum as electricity, and I don't think it can without some form of conductor or ions coming in contact with each other. So, doesn't electric potential have to get released as radiation if their is too much insulation for it to conduct elsewhere? Or can charge build up indefinitely within a vacuum without resulting in photon emissions? Sorry if this is too divergent from the OP. Maybe a more specific related question is whether negative voltage is a comparable concept to negative temperature where temperature is measured in C or some other scale whose zero-point is absolute zero? Perhaps you should start your own topic to discuss this? I'm not sure it's directly relevant to the OP's question. Negative voltage is not directly comparable to negative temperature. Voltage measures a comparative value (potential difference), whereas temperature is an absolute value. Link to comment Share on other sites More sharing options...
DrRocket Posted March 2, 2011 Share Posted March 2, 2011 Can Negative DC voltage be measured? If yes then how and what will be the range of its values. Yes. Flip the polarity swithch on your voltmeter, Or just interchange the leads. The range (in absolute value) is independent of polarity. Link to comment Share on other sites More sharing options...
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