Automatic oil transfer (cdi?)

[boscoe99]

To add further fuel to this fire.
A voltmeter has to consume some POWER to give a reading: it is a large resistor in parallel to a circuit measured.
When we measure current, or use an amp meter, we are using a low resistor in series to a circuit.
We, however, in measuring current are only ABLE to measure voltage over a resistor: an amp meter is really just a volt meter in parallel with a very small resistor.
So we only need to really measure VOLTAGE to calculate amps or ohms, and if one wishes watts!😏
Voltaire wins, the other three people rode on the back of his discovery.

Isn't a voltmeter really an ammeter set up to indicate voltage? A galvanometer?

[boscoe99]

To add further fuel to this fire.
A voltmeter has to consume some POWER to give a reading: it is a large resistor in parallel to a circuit measured.
When we measure current, or use an amp meter, we are using a low resistor in series to a circuit.
We, however, in measuring current are only ABLE to measure voltage over a resistor: an amp meter is really just a volt meter in parallel with a very small resistor.
So we only need to really measure VOLTAGE to calculate amps or ohms, and if one wishes watts!😏
Voltaire wins, the other three people rode on the back of his discovery.

I thought we needed two of the three variables to calculate the third and unknown variable.

We can have one voltage. Say 12.7 volts. There can be many many different resistances and amperes with that one voltage.

[zenoahphobic]

Isn't a voltmeter really an ammeter set up to indicate voltage? A galvanometer?

I look at it this way. You can have voltage but no current, but you can't have current without voltage; so what is the fundamental thing with "electricity"?

I just can't help thinking back when all this stuff was discovered, hypothesised, and what was described to be true, a good idea or simply a "law". Can you imagine the arguments that were often across language barriers for many years. People would have been executed, burnt at the stake etc. etc........we now are very civil discussing this... how times would have been very difficult to put down this science, particularly in a long period when science was a threat to religion, and religion ruled the world.

Now getting back to a voltmeter or ammeter. The difficulty with electricity is that by and large it can't be seen, heard etc; that is why humans didn't know it existed for such a long time....but there were hints like lightning, hairs standing on end, electric eels............, so we needed ways to make it visible and measurable. This came in many ways but not until the relationship between electricity and magnetism was discovered that the modern voltmeter was made from a moving coil with a pointer, that moved against a spring, the more voltage given the greater the force against the magnet.

I guess early versions would have consumed a fair amount of energy, so great that it affected whatever was measured to the point that It was not properly understood what was being measured. It was only when things were "miniaturised" enough that the voltmeter consumed little current and therefore had a high resistance. Voltmeter or ammeter or what else, recorded in history, early contraptions just showed "electricity".

I believe volts or EMF or electrical potential is all that can be measured so a current meter is just a converted volt meter fundamentally. Where we have such definitive terms etc is from the simultaneous development of mathematics (I think the guy that said numbers go on forever, infinity, got his head cut off).This included concepts like:in parallel or in series. However it will be argued we can measure current without putting a current meter in series. True. We utilise the magnetism generated by the flow of electricity in a different way because magnetism radiates outwards so we can detect it outside around the conductor . Someone might point out "electric field" in all this, but I like to simplify.

I said all you need is a voltmeter. This comes from the Boy Scout, to be resourceful and using as little as possible to achieve many things. A bit like the industrial revolution one machine can build a different machine, that can build another machine.......to where we are now. So probably if you only have a voltmeter ( to find wiring faults) you need other things like known resistors, 12v source, light bulb, tools, wire,etc.etc. We had to only use a voltmeter in science to determine all these units in a circuit: volts,amps,ohms,watts,kwhrs.

[zenoahphobic]

Isn't a voltmeter really an ammeter set up to indicate voltage? A galvanometer?

Nearly right, You got that out of order.

I meant to say in practical everyday wiring use we don't actually use the term galvanometer.
But correctly, a voltmeter is made with a galvanometer (the moving coil reacting to magnetism bit) with a large resistor in series. An ammeter (ampere meter) is a galvanometer with a small resistor shunted across it.

So it is the galvanometer that "indicates" voltage and amperage.

[99yam40]

that would only be on analog meter movments

[zenoahphobic]

that would only be on analog meter movments

Yep, digital obviously displays differently but it obtains the source fundamentally the same.