I have copied this from the old "Questions to BWMA"Board.

Bud wrote

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Stan:
Amps are everyday units surely? Fuse ratings, electric cable etc.
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Stan, I challenge you to find someone besides a scientist, engineer or person interested in studying measurements who can answer the following two questions correctly.

1. What does an amp measure? Power, current, voltage, or charge?
2. If you have 1 amp, how much charge is flowing per second?

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Bud, you have not seen electrical plugs in the UK. Each plug has a fuse in it - usually 13 amps, though appliances such as lamps etc use lower rated fuses. Also, it is not possible to buy 2-pin adaptors (used for electri shavers) that have a fuse greater than I think 500mA.

Anybody with a modicum of electrical knowledge knows the difference between amps and volts - after all we often hear about changing the voltage from 230V to 110V when we go to the US and the way in which everybody in teh UK comes into contact with fuses makes them aware of what a fuse is.

As an electrical engineer, I, of course, am cheating but an ampere measures current and is one coulomb per second which answers the charge question.

I think most Americans would have an idea of what the ampere is, but not the coulomb. House electrical wiring is mostly 15 A circuits, except code requires two independent 20 A circuits in the kitchen, minimum. Products are not individually fused, and we have to be aware if we overload a circuit, the breaker will blow. Blow it a few times and you learn adding the amperage of loads, and ensuring the total load is below 15 A, is pretty simple.

Most Americans would also understand the watt (and kilowatt-hour) in terms of electricity, but would not understand that the kilowatt is an acceptable way to rate the power output of an internal combustion engine.

They would have only a general idea of the volt, mostly that the voltage of the source should match the rated voltage of the hardware and overvoltage will blow it up.

Even as an engineer, I have a poor understanding of what a katal is, or what to do with one when I have it. (I was hoping it was mispelled cattle, and I could eat it, but apparently not so). So it gets my vote as the most "scientific" unit.

I don't know why only one letter of my name appeared, but that was me.

From that same thread, the candela.

I suspect most people wouldn't know what it is, but a few might make lucky guesses because it sounds like "candle." However, I am guessing that quite a few people would be aware of the derived unit "lumen," as it is commonly used to rate output of light bulbs, and particularly different technologies, tungsten, halogen, compact florescent, where just using watts breaks down.

I accept your point Bud that electricity is poorly understood by many.

However people are aware of this unit as a measure (strength of some kid) for fuses and if they replace one it has to be of the correct rating. They only think of it in comparative terms but they DO use it.

You could say the same thing about the volt. Ask people to explain what that is. Yet people know high voltages are dangerous and things like batteries are typically only a few volts. Again they know that a battery or mains adapter should be the correct voltage for the appliance etc.

My point was that most people do not know exactly what these electric units mean. Everyone knows that batteries can be labelled as "3 volts", but most people don't know what these 3 volts measure. Similarly, just because they know that the voltage of the appliance must match the voltage of the plug doesn't mean that they have understood the concept. For example, I am positive that 99.9% of non-scientists in the world do not know that voltage is potential energy per unit of charge.
By the way, I am familiar with UK-style plugs.

"""My point was that most people do not know exactly what these electric units mean. Everyone knows that batteries can be labelled as "3 volts", but most people don't know what these 3 volts measure. Similarly, just because they know that the voltage of the appliance must match the voltage of the plug doesn't mean that they have understood the concept."""

Not necessarily true. People just push the plug into the correct socket and the appliance works and nothing more is thought about it. Only when they blow a fuse or start a fire are they clued in that something is wrong. As for batteries, they just stick in the correct number and size the appliace says it requires.

Even people who work with electrical equipment aren't always aware of the concepts. Many times when I asked a customer who called in to say his equipment was working what the current draw was, I was told the voltage applied. When I would say again, "no, the current!", they were confused. I then had to ask how many amps were being drawn by the device.

At least in the days of fuses people were more aware of current load because they had to change the fuses and replace it with one of the same value. Even then there were those who would replce fuses with coins. Now with circuit breakers, there is even less a need to know. When it blows, you just reset it.

This could all be easily corrected if the schools taught practical electricity to everyone.




"""By the way, I am familiar with UK-style plugs. """

Are you also familiar with the most popular plug in the world? The Schucko plug.