What is the voltmeter reading?

Answer 1

ANSWER

I asked my husband who's an electrician and he say's a voltmeter does what it say's it measures "volts".

ANSWER

Voltage is the potential difference between two points, thus a volt meter must be referenced somewhere (ie one probe connected to some location for comparison, often ground). You can think of voltage as the desire of electricity to flow. If you use a volt meter and measure an unused wall socket, you will read ~120 volts (AC, RMS), but there is no current (except the very small amount flowing through your meter), thus no energy (energy = power = voltage * current) is flowing from unused outlets.

A volt meter does not measure energy, it measures potential difference, or voltage.

ANSWER

[it is a WikiAnswers violation to delete a technically accurate answer so that you can substitute your own]

OK, what we've got here is information being expressed at different levels of understanding and usage.

(1) An electrician only needs to know that his voltmeter measures something called "volts", without being concerned what "volts" means. If his voltmeter reads 117 volts here and 235 volts there, he knows whether or not the circuitry is working properly.

(2) A person reading a school textbook is going to be subjected to oversimplification, creative use of langauge and analogy rather than technically correct facts, easily misinterpreted partial truths, and the occasional totally incorrect information. When people start ascribing human characteristics like "desire" to electrical circuity, and use outdated or generic words like "electricity", you know they are operating at that middle school or high school level textbook level.

(3) A scientist or engineer needs to understand what is going on at a level of mathematical accuracy and within the accurately integrated framework of the International System of units and quantities. There is no le Systeme International quantity called "desire", and energy most certainly does not equal power. At this 3rd level of understanding, the language is constrained by information that conform to the internationally agreed-upon set of standards that we consider to be"scientific fact".

At this 3rd level of understanding, there are 2 competing but equally rigorous and correct systems for describing "electricity"; the 2 systems vary only by including or not including time as a factor. The system that does not include time is more fundamental, getting right down to the sub-atomic physics that drives electrical phenomena, so I prefer it. Let us call it FS for fundamental system. The popular le Systeme International includes time and is more likely to be encountered in textbooks of physics and engineering. It is almost always called SI.

So what does a voltmeter measure? FS explanation: As charge (measured in Coulombs) moves through a circuit, it must be driven by energy (measured in Joules). Voltage (or Potential Difference) is a measure of the amount of energy driving the charge at any point in the circuit. Voltage = energy/charge = Joules/ Coulombs=Volts.

The voltage always has to be measured between 2 different points in the circuit, so your voltmeter is telling you the difference between the energy levels at those 2 points. In order to read the energy levels, the voltmeter has to have a tiny amount of the charge move through the voltmeter; that's a critical understanding! The voltmeter can only read the energy difference by sampling some of the flow of charge. Having done that, your voltmeter can tell you in Volts the amount of energy driving the charge between the 2 points you selected.

So what does a voltmeter measure? SI explanation: As current (measured in Amperes) moves through a circuit, it must be driven by power(measured in Watts). Voltage (or Potential Difference) is a measure of the amount of power driving the current at any point in the circuit. Voltage = power/current= Watts/Amperes=Volts.

The voltage always has be measured between 2 different points in the circuit, so your voltmeter is telling you the difference between the power levels at those 2 points. In order to read the power levels, the voltmeter has to have a tiny amount of the current move through the voltmeter; that's a critical understanding! The voltmeter can only read the power difference by sampling some of the flow of current. Having done that, your voltmeter can tell you in Volts the amount of power driving the current between the 2 points you selected.

The only difference between the two explanations, as I said, is a time factor. Power is the energy delivered per second of time. Current is the charge flowing per second of time. So when you compare Power and Current, it is mathematically and physically identical to comparing Energy and Charge. The time factors cancel out and you're left with only a language difference.

If a circuit is energized or powered, as a convention we say that the operative voltages exist even though there is no charge or current flowing and the voltages are theoretically infinite. This is in recognition that the energy or power is instantly accessible whenever a load is introduced into the circuit.

Answer 2

voltage is read with a voltmeter. You set your meter controls to proper voltage source AC or DC, proper voltage range. 120, 240 or 600. Make sure setting is highest if you don't know what to expect. Read the meter across the the battery terminal, observe correct polarity or across the load or supply in an AC voltage. Lower your voltage setting to closest scale for most accurate reading.

Answer 3

voltage in a circuit (also known as potential difference p.d.)
A voltmeter or multimeter is an electrical instrument capable of measuring voltage, current, and resistance. Digital multimeters have numerical displays, like digital clocks, for indicating the quantity of voltage, current, or resistance. Analog multimeters indicate these quantities by means of a moving pointer over a printed scale.

Answer 4

DC (direct current) voltage. Its value does not change between positive and negative, and often remains constant. DC voltmeters are simpler because they do not need to handle changes in the signal being measured.

Answer 5

At its core, a voltmeter contains a sensitive ammeter. A large resistor is placed in series with the ammeter. Voltage, then, induces a current which causes the ammeter to indicate proportionally to the voltage.

For instance, in a Triplett 310-C that I have, the ammeter has a resistance of 460 Ohms and a full scale current of 50 µA. On the 3 V scale, a resistance of 59,540 Ohms (Actually 60 K Ohms) is placed in series, so that 3 V will induce a current of 50 µA.

60 K Ohms (1%) is used because it is within 1% of the theoretical 54,540, and the instrument's published accuracy is only 3%. The meter's impedance is rated 20 K Ohms per volt, which was typical for the time. (The instrument is 35 years old, and was considered mid quality at the time.)

Answer 6

If you are talking about house wire, touch the ends of the black and white wires. The black and ground wires will work the same.

Answer 7

Voltmeter measures potential difference between to points in Volts.

Answer 8

To read the voltmeter, make use of the test leads.

Answer 9

A voltmeter tells volts. A volt is a joule per coulomb or a normed coulomb per metre.