Ohms Law

Reminds me of a newspaper headline about a mental patient who raped a nurse and escaped from an asylum:

"Nut Screws and Bolts!"

-from Catch 22

Perhaps it can't be, due to the units.

e.g. which is greater, a mole of buckets, or a bucket of mole?

Be careful with the plumbing analogy. Water is incompressible, so a short piece of 1/2" pipe in series with a long piece of 1" pipe will behave pretty much as it would if the entire pipe were to be replaced by 1/2". That's why a faucet works.

Electricity through a wire is controlled by the size of the wire times its length. Replacing a 1" section of a 10' piece of 12Ga wire with

Norm Strong

Well, all analogies break down else they wouldn't be analogies. This one is for 12yr olds, so one shouldn't expect too much of it.

However, we should also not underestimate the difficulty of understanding abstract concepts such as 'energy' and conservation thereof. It is not at all obvious and even now it seems more like a bookkeeping trick that works than anything 'real'. Which is why bad SF is replete with phrases such as 'pure energy'. Whatever that is.

BTW, in String Theory what are Strings made of, and what is its inherent properties?

Strings are made out of mathematics. Their most important property is that their existence will always be completely untestable.

BTW, analogies are useful only when they make sense. Saying electrical current is like the flow of water isn't useful enough to be persued in textbooks, for example. However, saying that LC oscillators are like mass and spring systems makes much more sense, because they are governed by the same differential equations.

However there was the little issue of Helen being only twelve years old when she was taken!

Here that would trigger an "Amber Alert"

Well, I thought it cam from the phrase "Not worth a tinkers dam" Since that little bit of clay is chipped away after the metal is poured! Not Metric!

Actually, it has been seriously proposed that Strings are, literally, mathematical propositions. Maths made physical. Chaitin's 'All Universe Hypothesis' is relevent here.

So what analogies are, for 12yr olds?

I was just over at the exploratorium in SF last week with my daughter's science class. . It's a hands-on science museum near the Golden Gate bridge in San Francisco.

I don't recall any attempts to explain such concepts as current flow.

Most of the exhibits were trying to teach physics, biology, acoustics, computers, stuff like that. There was one cool exhibit where they were showing Lissajous pattern on an oscilloscope screen, and allowed you to adjust the frequency in both the X and Y direction to see different patterns. Another exhibit showed lissajous patterns that were formed by the motion of the top of a vertical steel rod with a flattened area when it is plucked. I had fun pointing out the similarity between those two exhibits.

Electronics, other than the solder it together kind, isn't really accessible until one can get the basic math, I think. You just can't design, or even analyze it using fluid flow analogies.

BTW, I thought it would be pretty cool to build a lissajous pattern generator for my oscilloscope. The one they had at the exploratorium allowed adjustments with an accuracy of 0.01 Hz in the oscillators for X and Y. I was wondering if there was a simple analog circuit they were using to do that, or whether it was digitally created using a microprocessor... The frequency range IIRC was between 0 and 400 Hz.

Duh.

and

The motoring world and its granny "accepts" exeeding the speed limit.

And someone else wrote about dam and damn. The latter is a contraction of damnation.

Well, for each channel, there is an LED frequency display which indicates 5 digits, xxx.xx. By adjusting a knob, you can adjust the frequency displayed. There are two knobs/frequency displays, one for each channel.

The main display shows the lissajous figure, and is obviously an oscilloscope display. The figure changes based on the frequencies. The motion of the figure stops when the frequencies are set properly. It seemed pretty sensitive to even very small differences (0.01 Hz), but I could be misremembering the actual resolution. It was difficult to get it to stop completely, and had the feel of an analog pot, with missing spots.

The government officially doesn't, but unofficially welcomes the extra revenue from tickets.

Actually, all the references I see on the web capitalize them, so I guess so. They are apparently named for Jules-Antoine Lissajous.

It would be pretty easy to do a quite accurate frequency sine wave with a dsPIC chip and a D/A converter, but it seems like more than is required. My (analog) signal generator is pretty good at very low Hz, but not that accurate. OTOH, the display may have been inaccurate, simply indicating the voltage of a voltage divider or something that was used to control the oscillator.

It was a wonderful exhibit, though.

Rich The Philosophizer wrote

And black is white.

Not really:

n. The act of damning or the condition of being damned.

1. Condemnation to everlasting punishment; doom.
2. Everlasting punishment.
3. Failure or ruination incurred by adverse criticism.

No references to a contraction under either definition.

ESSENCE - vanilla?

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have

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potential.

is

But

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battery)

List

LOL

Cheers Terry

----------- An I sure hope that the load at the end of the wire is the controlling factor. I like to get what I pay for in useful work, not losses in the wire.