Das Java-Applet
demonstriert Skalar-Wellen in 3 Dimensionen, z. B. Schallwellen.
(Elektromagnetische Wellen bestehen aus Vektoren, daher wird dies im Applet
nicht ganz korrekt dargestellt.)
Wenn das Applet
startet, wirst Du rote und grüne Wellen sehen, die sich von einer Punktquelle
in der Mitte des Würfels entfernen. Die Farbe gibt dabei jeweils den
akustischen Druck an. Die grünen Bereiche sind negativ und die roten positiv.
Das erste, was Du
tun solltest, wenn das Applets startet, sind die Einstellungen für Deinen
Computer anzupassen. Klicke zunächst die "Alternate
Rendering"-checkbox, falls noch nicht geschehen. In Abhängigkeit von
Deinem Browser wird die Bewegung flüssiger oder das Bild beginnt zu stottern.
Falls das der Fall ist, entferne das Häkchen wieder.
Als nächstes
erhöhst du die Auflösung unter "Image Resolution" soweit wie es geht,
ohne dass das Applets zu langsam wird. Falls die Bilder schon stocken,
verringere die Auflösung. Eine weitere Alternative zur Kontrolle der
Geschwindigkeit ist der "Simulate Speed"-Button. Es verbessert zwar nicht die Bildrate,
aber die Wellen werden dadurch schneller.
Im Setup-Menü
kannst Du folgende Einstellungen vornehmen:
- Point Source:: einzelne
Punktquelle inmitten des Würfels, die Wellen in den Raum aussendet.
- Pinhole: ebenfalls
nur eine Einzelquelle, die aber an einer Würfelwand liegt.
- 2 Point Sources: Hier handelt
es sich um zwei Punktquellen, deren Wellen interferieren. Mit zunehmender
Frequenz wird das Interferenzbild deutlicher. Der "Source
Separation"-Regler gibt die Entfernung der Quellen zueinander an. Mit
"Phase Difference" kann die Phase der Wellen relativ zueinander
angepasst werden. Über "Balance" lassen sich die jeweiligen
Stärken der Wellen anpassen, ähnlich wie bei einem Radio.
- Dipole
Source: Demonstration eines Dipols
- Lateral Quadrupole: ein
Quadropol, bei dem die Quellen in einem Viereck angeordnet sind
- Linear Quadrupole: ein
Quadropol, bei dem die Quellen in einer Linie angeordnet sind.
- 2 Pinholes: zwei
Punktquellen, die sich an einer Würfelseite befinden.
- Single Line Source: einzelne
Linienquelle, die zylindrische Wellen aussendet.
- Single Slit: demonstriert
Wellen am Einzelspalt.
- 2 Line Sources: Zwei
Linienquellen, deren Wellen interferieren. Du hast die gleichen
Einstellungsmöglichkeiten wie bei "2 Point Source".
- Double Slit: Interferenz
am Doppelspalt.
- Triple Slit: Interferenz
am Dreifach-Spalt.
- Plane Wave: Ebene
Wellen, die sich in eine Richtung bewegen.
- 2 Plane Waves: Zwei sich
überlappende ebene Wellen. Du kannst über die Regler "Theta" und "Phi" die
Richtung der ersten Welle steuern, dabei änderst Du lediglich den Winkel
der Ausbreitungsrichtung in sphärischen Koordinaten. Auch die Balance kann
verändert werden. Befindet sich der Schieber ganz links, ist nur die eine
Welle präsent, dies ist besonders hilfreich, um das Gefühl für die Steuerung
von Tehta und Phi zu erhalten.
Mit "Stopped"
kannst Du das Applet anhalten und wieder starten.
Über Checkbox "Show
Intensity" kannst Du Dir die Wellenintensität anschauen im Raum anschauen
"Show Sides"
zeigt Dir den akustischen Druck (oder Intensität) ebenfalls an, allerdings nur
an den Seiten des Würfels.
"Mouse popup"
hat zwei Funktionen. Über "Mouse = Adjust Angle" kannst Du bei
gehaltener linker Taste den Würfel drehen, "Mouse = Adjust
Zoom" erlaubt
das zoomen.
Über Slice popup erhältst du verschiedene
Querschnitte mit dem Interferenzbild. Bei "No Slicing" siehst Du den
gesamten Würfel.
Mit "Simulation
Speed" änderst Du die Geschwindigkeit der Oszillation.
Der "Brightness"-Regler
kontrolliert die Helligkeit (wie beim Bildschirm), damit wird das Erkennen
schwacher Wellen erleichtert.
"Image
Resolution" kontrolliert die Auflösung, dabei gilt, je höher die Auflösung,
desto langsamer das Applet.
"Frequency" ändert
die Frequenz der Wellen.
Klicke hier, um zum Applet zu gelangen.
(Übersetzt von Markus Scholz.)
java@falstad.com
A far higher place must be assigned to Judaism among the competitors for the allegiance of Europe. The cosmopolitan importance at one time assumed by this religion has been considerably obscured, owing to the subsequent devolution of its part to Christianity. It is, however, by no means impossible that, but for the diversion created by the Gospel, and the disastrous consequences of their revolt against Rome, the Jews might have won the world to a purified form of their own monotheism. A few significant circumstances are recorded showing how much influence they had acquired, even in Rome, before the first preaching of Christianity. The first of these is to be found in Cicero’s defence of Flaccus. The latter was accused of appropriating part of the annual contributions sent to the temple at Jerusalem; and, in dealing with this charge, Cicero speaks of the Jews, who were naturally prejudiced against his client, as a powerful faction the hostility of which he is anxious not to provoke.330 Some twenty years later, a great advance has been made. Not only must the material interests of the Jews be respected, but a certain conformity to their religious prescriptions is considered a mark of good breeding, In one of his most amusing satires, Horace tells us how, being anxious to shake off a bore, he appeals for help to his friend Aristius Fuscus, and reminds him of217 some private business which they had to discuss together. 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The same poet elsewhere intimates that whenever they found themselves in a majority, they took advantage of their superior strength to make proselytes by force.’332 And they pursued the good work to such purpose that a couple of generations later we find Seneca bitterly complaining that the vanquished had given laws to the victors, and that the customs of this abominable race were established over the whole earth.333 Evidence to the same effect is given by Philo Judaeus and Josephus, who inform us that the Jewish laws and customs were admired, imitated, and obeyed over the whole earth.334 Such assertions might be suspected of exaggeration, were they not, to a certain extent, confirmed by the references already quoted, to which others of the same kind may be added from later writers showing that it was a common practice among the Romans to abstain from work on the Sabbath, and even to celebrate it by praying, fasting, and lighting lamps, to visit the synagogues, to study the law of Moses, and to pay the yearly contribution of two drachmas to the temple at Jerusalem.335 Jeff’s hand was quietly coming down. “What happened to you?” begged Sandy. “Something new has come up, sir. I was waiting there by my ship a good while back, and I heard another one cruising and spiraling, shooting the field, I guess, because he came in and set down. My crate, just the way you ordered, was down by the grove, not in plain sight in the middle of the course. But Jeff set his ship down, left the engine running, and went off. I stayed hid to see what would happen, but when he didn’t come back, I thought I’d better go and find you—and see if it meant anything to you.” She stood alone, with the sticky, wet knife in her hand, catching her breath, coming out of the madness. Then she stooped, and pushing the branches aside felt about for her pistol. It lay at the root of a tree, and[Pg 80] when she had picked it up and put it back in the holster, there occurred to her for the first time the thought that the shot in the dead stillness must have roused the camp. And now she was sincerely frightened. If she were found here, it would be more than disagreeable for Landor. 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