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Flat Earth Academy- Science

Measuring- and instruments

Part of what "doing something scientifically" is measuring. Measuring is a huge part of what scientists and engineers ("practicing scientists"!) do !!!

Many important milestones in science didn't come earlier than they did because they had to wait until a particular instrument had been invented. How could doctors have known much about microscopic pathoghens before microscopes, for instance?

Every doscipline has it's own special instruments. This page, however, is going to look at some things they all have in common.

In particular, we are going to look at the choices people have to make when designing an instrument for a particular purpose.

Pick two...

There's an old saying that amuses me... and is wise, I think.

When you hire someone to do a job for you, you want it done quickly, done well, and done inexpensively.

You can have two of those. The job can be...

The above applies to the making of instruments for science, too.

Further design considerations

In the pages of the Flat-Earth-Academy, you will find invitations to make our own scientific instruments.

In the course of those projects, I hope you will get a better idea of the problems that arise when you are designing instruments.

You want your instrument to be...

The first three are simple enough.

Large range

The "range" of an instrument is the difference between the smallest thing it can measure, and the biggest. A tool to measure the dimensions of a building wouldn't be very convenient to use at your desk for measuring things up to, say 30 cm long, would it?

While the example is obvious, trivial, it illustrates an important parameter of any instrument.

Accuracy

If you measure something several times, and always get nearly the same answer, your instrument is accurate.

It may be wrong! It may say the pencil lead is 0.6 mm thick when it is actually 0.9 mm thick. But if it says "0.6" every time, that's good in its way. Science is about making predictions, and if your instruments give you different answers when you measure the same thing, it doesn't help you disciver rules which allow predictions!

Precison

Besides being accurate (see previous section), it is good if your instrument is as precise as possible. Scientist "A"'s instruments should give him the same answers as Scientist "B" is getting from his instruments when each measures the same thing as measured by the other.

(I commend a good further discussion of "accurate" and "precise" to you. (It is just four short paragraphs.)

No... it's not "obvious"

You, might think that the things on this page are "obvious"... but if you dismiss it thus, you will miss a lot of fun.

Trying to come up with your own instruments, or even just studying those made by other people can be a lot of fun. Especially if you think about the different parameters upon which an instrument can be evaluated.

In making your own instrument, getting something that "works" is a great first step. But once you've achieved that, what improvements can you come up with. Can you, without making too hard to set up, say, or too expensive, say, make it more accurate? Give it a better range?

Where do inaccuracies come from? Can you stop, or reduce them by some change in the design?

I hope that has helped you to see instrument design in a new light?



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