Say u have a voltmeter (dc) and whack the wires straight into a powerpack.....the voltmeter often registers a few volts below what is should be. What can cause this? Assumeing that it is actually 12V its generating?.....I cant find this anywhere. Abbreviated Its apparantely 3 letters long...what im looking for.....Any help would be appreciated. Sorry i cant explain more.....just shows how hard this wud be to search google or yahoo for lol.
2006-11-15 01:41:12 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Physics
II think the letters you are looking for are RMS: root mean square. The value you see on a voltmeter is the RMS value of the voltage, which is about 70% of the zero-to-peak voltage of the waveform.
RMS can be calculated by taking the input voltage waveform, say a sine wave, squaring it (which makes all the voltages positive), taking the mean (average) voltage, and then taking the square root (to undo the value change from the squaring operation while leaving the value positive).
2006-11-15 01:47:25 · answer #1 · answered by poorcocoboiboi 6 · 1⤊ 0⤋
The three letter word you are looking for is "OHM"
An ohm is the unit of resistance.
The more the resistance, the less the voltage.
Your voltmeter may have some resistance between the two electrodes which can result in a false reading of the actual voltage ,
2006-11-15 02:15:57 · answer #2 · answered by mindtelepathy 5 · 1⤊ 0⤋
The thing that causes a voltage drop is the internal resistance of a battery. I don't know of an abbreviated version of this, but it's definitely what causes a battery to read a lower voltage than the rating.
I hope this helps!
2006-11-15 01:48:35 · answer #3 · answered by Anonymous · 0⤊ 0⤋
There ate a number of things
1. Are you sure that your measurement is wrong?
2. Are you sure your ranges are set properly ?
3. Calibrate your meter (or check its calibration against a standard or a known value).
4. Are you measuring the source under load? The load may draw current from the weak source creating this effect.
Can you supply a more detailed information?
2006-11-15 01:51:32 · answer #4 · answered by Edward 7 · 0⤊ 0⤋
If it were AC instead of DC I could agree that
your looking for RMS. but RMS is not related
to DC voltage.
The leads to your voltmeter do have some resistance
which can make the metter read SLIGHTLY less than
the actual value, but not VOLTS lower...
Old meters read peak voltage, new meters show it
in RMS values....
2006-11-15 01:50:45 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Load or resistor
2006-11-15 01:54:12 · answer #6 · answered by svs power 2 · 0⤊ 0⤋