IN the December issue of “QST” the following Japanese letter was published, and the Secretary offered to pay $5.00 for the best answer:
To Honorable Mr. Radio Secretary Tuska,
Honorable Relay League, America
I ask to know. When condenser made separators of glass we know dialectrics much pressed by electricity. This much sure, why, tests made show it. Honorable writers of English make tests and demonstration that metal can be vanished and all the same when new metal comes to condenser, yet discharge comes too the same.
Why thus we see plain that dialectric heart of condenser.
Then now. I ask to know if air I use no glass for important dialectric does it obtain pressed? Like glass? Honorable American teachers tell me yes. Air—glass—Mica all same without difference among them.
Then now again how? Suppose I have air variable condenser and I the air vanish blowing by breath. Goes away quickly the air. How goes my electricity charge? Goes it too? I think me not. Then how charge gets back?
Explanation me Honorable Radio Secretary for which accept my assurances most distinguished consideration.
|S. P.||Why this write typewriter, you Japanese write mostly not know.|
A great many letters were received and we are sorry that we cannot publish all of them. We are printing the best letters. Two of the writers seem tied for first place. The judges were unable to decide just who sent in the best letter. They were all very close together so it was finally decided to divide the five dollars between Mr. Felix and Mr. Wolfe. The others were so close behind that they really deserve a reward and the publishers of “QST” have entered their names for a year's subscription.
Mr. Felix answered the questions directly. His letter was short, technical, and humorous. Our friend, 3AFM, certainly wrote his letter in a humorous style, with a laugh to a line and several grins thrown in. Mr. Wolfe did not give much of an explanation, but he certainly “takes the cake” for humor.
ONE OF THE WINNERS
Dec. 4, 1915.
To Kathis Kathkan,
It certainly looks to me as if you had been a victim of one of those confounded “self-taught English” systems, and if such is the case you sure have done well with the material at hand. For looking over your communication, we're compelled to admit that every word you have used is an English word, and your spelling, on the whole, is good. But Kathis, old top, you've got the words in the wrong bins. Your construction sure beatser-is very bad. If it costs you as much effort to write that thing as it has cost us to read it, there's been enough energy wasted to get a press message from pole to pole and at that, I don't believe we quite get you.
Now Kathis, (Hang it! Every time I come near calling you Hasheesh). I'm no scientific sharp nor expert mathematician, but I’m going to have a shy at the Sec's. five. I gather that you have been tampering with that interesting chunk of apparatus, the condenser, and it’s got you up a bamboo, so to speak. (Notice the delicate handling of sidewalk English to meet local conditions) and let me say right here, Hasheesh—er—Kathis, that if you try one experiment you mention, you’re very liable to get knocked clean out of that bamboo. This “vanishing” of metal plates from off a condenser after they have been “pressed” by electricity isn't all it's cracked up to be. It's very much like interfering with lightning which is hurrying to keep an appointment. If you've got a couple of two quart Leydens, with a fairly decent transformer doing the "pressing"—beware! And after that, beware some more. And if you really must try the experiment, let your German assistant or your mother-in-law “vanish” those jar coatings. The best thing to do is to avoid “vanishing” the plates. Take the “Honorable writer of English's” word that it can be done.
Then now, Kathis, (pardon plagiatism, old top) it looks to us as if your ideas of dielectrics are a little hazy. Kind of foggy, so to speak. Suppose you give your honorable writer of English another battle. Tune him in, fine, hash——Kathis, and copy him carefully, and see if he tells you that dielectrics are “all the same without difference among them.” Get a line on what a dose of castor oil will do to a poor little .0015 receiving variable which has been struggling along with air as a dielectric. The now again, Kathis, old fellow, I think you're a good skate, and if I were you, I wouldn't waste any time “vanishing” the air dielectric by “blowing by breath.” After you have “vanished” the plates, and wonder “how goes my electricity charge” I assure you, old pal, that in spite of the fact that you “think you not” your electricity charge “goes it too," and darned quick.
Just one word more, Kathie, old kid. It's blamed hard under the circumstances to “explanation you.” It may be that you have gotten a condenser confused with a storage cell. Under certain conditions it is possible to "vanish" the electrolyte from a storage cell and put in an entirely new batch. In that case, your electricity charge “goes it not.” See?
So long, old can. My call is 3AFM, and if you ever solve the secret of freak transmission, give me a wail. These days of amplifiers it's possible to hear Jerusalem on a clear, cold night, anyway.
A POETICAL ONE.
Oh, Kathis Kathkan, Wireless Jap,
Explanations you need certainly sure;
Your education, I think, it lacks.
Why should you a radio student ask:
Where goes the charge in a chunk of air?
The charge it stays when the metal is near;
Blowing admits of no avail,
But remove the plates, now where the
Charge has scattered far and wide
Nothing to hold it; why should it stay?
The more it scatters the weaker it grows,
Weaker and weaker as the distance squared.
Finally it vanishes and disappears.
So goes the charge of a chunk of air.
ANOTHER PRIZE WINNER, WHICH DESERVES THE REWARD.
To Honorable Kathis Kathkan,
Distinguished Radio Student,
In Care of the Honorable Post Office Box 1155,
High Hyancus, Excellent Japan.
You aks know; I write tell. When charge condenser, dielectrics pressed much of electricity.
Air—glass—mica dielectrics; all same, no difference, dielectrics much pressed when charge condenser. So much sure.
Electrons one side condenser try jump other side.
Air, glass, mica, all same. Always try jump.
One side too few electrons: Then, now, other side too much. Suppose air, I have variable, I air vanish, all the some, condenser much pressed. Electrons from side with too many try hop side of too not enough.
Vanish I air quickly, I blow, charge stay, electrons try yet jump. Charge no never go. You think you not—you think just.
528 Riverside Drive,
Mister Radio Secretary
Egyptian radio am me all same for railroad and war and me want race for Japanese ask to know condenser electricity where goes if blow its air by breath way me say yes sure away away blow but not, electricity charge of condenser dielectric all same blow no certainment not cause given good books why condenser charge he lives by the space and him is ions what you call english words so no man him blow he breath away space impossibly so all same now you send me five dollars if you please from
MURAD BEY ALLID,
Egyptian Radio Operator.
Count Murad Bey Allid neglected to give his address. The Count is evidently quite a radio expert.
A SERIOUS ANSWER TO K. K.
By E. E. House, Battlecreek, Mich.
In speaking of a condenser, the dielectric is a very important factor, but no more so than the metal plates which are the other part of this instrument. Yes, under certain circumstances, the dielectric of a condenser is very hard pressed, even to the point of puncture after which a condenser is useless.
If the dielectric is glass, the pressure on the glass is equal to the applied voltage, the area of the surface receiving the charge, and the time of charging. Using 20,000 volts as a unit and applied to a small condenser, we find this voltage in the normal air pressure of 15 pounds per square inch will break down the air between two points which are the opposite sides of potential, and one inch apart.
If the 20,000 volts are applied to a small condenser, and a gap of one inch is placed across the same, we find the condenser will charge and discharge several hundred times per second. Taking the pressure from a 60 cycle or 120 frequency per second, it will discharge several times per period. Open up the gap and the discharge will be less frequent, while the condenser voltage will run up to about thirty thousand. The discharge will be prominent of the 120 frequency of the applied power. Then close gap to one-half inch and the discharge will increase to several hundred thousand and just hiss.
This condition, of changes in the discharge frequency, may be developed by changing the area of the condenser. Making the condenser large requires a longer period to charge and a less frequent discharge will be the result. It is possible to make a condenser so large that it will absorb practically all of the applied E. M. F.
The thickness of the dielectric, for a given pressure depends on its insulating quality. Mica and glass rank high, while air is low. The thickness of the dielectric also depends on the area of the condenser, the time of charging, and discharging in proportion to the applied potential. Yes, air can be used as a dielectric, but is of little value in its natural condition. By pumping air into a tank which holds the condenser plates, we can use it as a dielectric, because its insulating qualities increase with pressure. Arlington uses condensers insulated by air at 250 pounds pressure per square inch. If I am not mistaken, a potential of 18,000 volts is applied
to this condenser.
The insulating qualities of air are reduced by heating of the condenser plates and by reductions in the air pressure. If the plates are put in a vacuum, there is practically no dielectric between them.
In speaking of the vanishing metal, I think Kathis Kathkan referred to the light tinfoil in a condenser which is sometimes eaten away by the brushing of too high a voltage. Copper, brass, or aluminum will not eat away like the foil.
P. S. The typewriter is used by Americans because it is considered a much neater form of letter writing. Most men are not good penmen when in a hurry, so the typewriter is much faster than handwriting. I may also add that the hand writing of different men shows much of the character of the man and this is objectionable in some lines of business.
MR. ALLEN’S SOLUTION OF KATHKAN’S PROBLEM.
When a condenser is charged, one set of plates is charged positively and the other negatively. This fact gives rise to a tendency for a spark to pass between the plates and thus equalize the charge. The dielectric, however, prohibits the passage of a spark. Hence, there is a great pressure or stress on the dielectric.
Contrary to general opinion, the seat of the charge of a condenser is not in the plates. It is in the dielectric. This fact may be shown by the following experiment:
Charge a Leyden jar, made with movable coatings, and set is on an insulating stand. Lift out the inner coating and then, taking the top of the glass vessel in one hand, remove the outer coating with the other. Test the coatings with an electroscope and no charge will be found. Bring the glass vessel near a pile of pith-balls. They will be attracted to it, showing that the glass is electrified. Now build up the Leyden jar by putting the parts together. The jar may be discharged in the usual manner. This experiment shows conclusively that the seat of charge is in the dielectric. The same is true of any dielectric whether glass, mica, air, oil or paper. All dielectrics act similarly and so they are all subjected to a stress whenever a condenser is charged.
It would be impossible “to vanish” the air from a variable air dielectric condenser by blowing through it. Hence, there will always be some dielectric present. Since the dielectric contains the charge it is evident that the condenser will remain charged. If the condenser were placed in a vacuum, somewhat different results would take place, but it would require too much valuable space to explain these.
Westerly, R. I.