Part 1 (1/2)

Letters of a Radio-Engineer to His Son

by John Mills

LETTER 1

ELECTRICITY AND MATTER

MY DEAR SON:

You are interested in radio-telephony and want me to explain it to you

I'll do so in the shortest and easiest hich I can devise The explanation will be the siive and still make it possible for you to build and operate your own set and to understand the operation of the large commercial sets to which you will listen

I'll write you a series of letters which will contain only what is important in the radio of to-day and those ideas which seem necessary if you are to follow the rapid advances which radio isSo and study In the case of a few youuntil you have finished those which interest you most I'll mark the letters to omit in this way

All the letters will be written just as I would talk to you, for I shall draw little sketches as I go along One of them will tell you how to experi of all You can find plenty of books to tell you how radio sets operate and what to do, but very few except some for advanced students tell you how to experiment for yourself Not to waste time in your own experiments, however, you will need to be quite familiar with the ideas of the other letters

What is a radio set? Copper wires, tinfoil, glass plates, sheets of et its ability to work--that is, where does the ”energy” come from which runs the set? From batteries or from dynamos That much you know already, but what is the real reason that we can use copper wires, es and to receive thes are ht call specks of electricity There are only two kinds of specks and we had better give theht names at once to save time One kind of speck is called ”electron” and the other kind ”proton” How do they differ? They probably differ in size but we don't yet know so very reat deal One is about 1845 tihteen hundred and forty-five tiet it started but it is just as et it to stop after it is once started or to change its direction and go a different direction The proton has the larger inertia It is the electron which is the easier to start or stop

How else do they differ? They differ in their actions Protons don't like to associate with other protons but take quite keenly to electrons

And electrons--they go with protons but they won't associate with each other An electron always likes to be close to a proton Two is company when one is an electron and the other a proton but three is a croays

It doesn'tcompany with provided only it is an electron and not another proton All electrons are alike as far as we can tell and so are all protons That means that all the stuff, orblocks, and all the blocks of each kind are just alike Of course you mustn't think of these blocks as like bricks, for we don't know their shapes

Then there is another reason why you must not think of them as bricks and that is because when you build a house out of bricks each brick must rest on another Between an electron and any other electron or between two protons or between an electron and a proton there is usually a relatively enorh space so that lots of other electrons or protons could be fitted in between if only they illing to get that close together

Soether I can tell you how if you will i Suppose Tom and dick don't like to play with each other and run away from each other if they can

Now suppose that Bill and Sam won't play with each other if they can help it but that either of them will play with Tom or dick whenever there is a chance Now suppose To toward each other to get up soa to join hi to be there too Meanwhile dick sees Bill and Sa and since they are his natural playether, and playing a great gaether

Whenever there is a group of protons and electrons playing together we have e call an ”atoames which electrons and protons can play, that is ninety different kinds of atoames differ in the number of electrons and protons who play and in the way they arrange theaether Then there is a ”molecule” Of molecules there are as many kinds as there are different substances in the world It takes a lot of h to see, for even the largest molecule, that of starch, is much too small to be seen by itself with the best possible microscope

What sort of a molecule is forroup together to play the larger gaaroups which enter into it are all changed around They keep together like a troop of boy scouts in a grand picnic in which lots of troops are present At any rate they keep together enough so that we can still call thearoups--that is with other atoms

What will the kind of atom depend upon? It will depend upon how ether in it to play their little garoups or atoa

Now the siame that can be played, and the one with the smallest nule proton and a single electron I don't know just how it is played but I should guess that they sort of chase each other around in circles At any rate I do know that the atoen” is fornified until they were as large as the moon and the earth Then they would be just about as far apart but the sen atoreat one to join with other atoh we can o from one molecule to another very easily That is what happens every tien atom leaves a molecule of the acid and then it isn't acid any roup either for it has lost sooes and joins with the stuff which gets stained But it doesn't join with the whole molecule; it picks out part of it to associate with and that leaves the other part to take the place of the hydrogen in the original molecule of acid from which it came Many of the actions which we call chees of atoms froen atoame with other kinds of atoms but it likes to do so with one of its own kind

When it does we have a as as is used in balloons