Bernstein, Aaron, Naturwissenschaftliche Volksbücher, Bd. 1/5, 1897

Table of Notes

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            <s xml:id="echoid-s150" xml:space="preserve">
              <pb o="9" file="019" n="19"/>
            Donner vergehen, die Entfernung des Gewitters berechuen
              <lb/>
            kann. </s>
            <s xml:id="echoid-s151" xml:space="preserve">Man braucht nämlich die Zahl der Sekunden nur
              <lb/>
            durch 3 zu dividieren und man erhält die Anzahl der Kilo-
              <lb/>
            meter, um welche das Gewitter noch entfernt iſt. </s>
            <s xml:id="echoid-s152" xml:space="preserve">Es beruht
              <lb/>
            dies darauf, daß der Schall ja gerade einen Kilometer in drei
              <lb/>
            Sekunden zurücklegt; </s>
            <s xml:id="echoid-s153" xml:space="preserve">um alſo etwa 5 km zu durchlaufen,
              <lb/>
            braucht er 5 ÷ 3 = 15 Sekunden. </s>
            <s xml:id="echoid-s154" xml:space="preserve">Erſt wenn Blitz und Donner
              <lb/>
            gleichzeitig wahrgenommen werden, iſt alſo ein Gewitter ſehr
              <lb/>
            nah und wird für uns gefährlich.</s>
            <s xml:id="echoid-s155" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s156" xml:space="preserve">Sehr wichtig iſt nun auch noch die Frage, wieviel Schwin-
              <lb/>
            gungen ein Ton in der Sekunde ausführt. </s>
            <s xml:id="echoid-s157" xml:space="preserve">Da zeigt ſich
              <lb/>
            denn, daß ein Ton, deſſen Wellenlänge 10 m beträgt und
              <lb/>
            der ja in der Sekunde 333 m durchläuft, 333:</s>
            <s xml:id="echoid-s158" xml:space="preserve">10 = 33 {3/10}
              <lb/>
            Schwingungen in der Sekunde ausführt. </s>
            <s xml:id="echoid-s159" xml:space="preserve">Man hat nun
              <lb/>
            herausgefunden, daß der tiefſte Ton, welchen wir noch zu
              <lb/>
            hören vermögen, etwa 25 Schwingungen in der Sekunde macht.
              <lb/>
            </s>
            <s xml:id="echoid-s160" xml:space="preserve">Alle Töne, welche weniger Schwingungen machen, können wir
              <lb/>
            nicht mehr hören. </s>
            <s xml:id="echoid-s161" xml:space="preserve">Die Töne in den beiden mittleren Oktaven
              <lb/>
            des Klaviers machen je nach ihrer Höhe etwa 200 bis 800
              <lb/>
            Schwingungen, die höchſten an 4000. </s>
            <s xml:id="echoid-s162" xml:space="preserve">Es giebt noch höhere
              <lb/>
            Töne, die aber ſchrill und unangenehm wirken und daher in
              <lb/>
            der Muſik nie verwandt werden, man kennt ſolche von 20 000,
              <lb/>
            ja 25000 Schwingungen in der Sekunde. </s>
            <s xml:id="echoid-s163" xml:space="preserve">Diejenigen Töne aber,
              <lb/>
            welche noch mehr Schwingungen machen, können wir wieder
              <lb/>
            nicht mehr wahrnehmen, und es iſt keine Möglichkeit vorhanden,
              <lb/>
            ſie wahrnehmbar zu machen.</s>
            <s xml:id="echoid-s164" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s165" xml:space="preserve">Wie aber wird es nun, wenn mehrere Töne gleichzeitig
              <lb/>
            erklingen? </s>
            <s xml:id="echoid-s166" xml:space="preserve">Werden ſich die einzelnen Wellen dann nicht ſtören
              <lb/>
            und gegenſeitig vernichten? </s>
            <s xml:id="echoid-s167" xml:space="preserve">Nun, aus Erfahrung wiſſen wir
              <lb/>
            doch, daß wir mehrere Töne oder Geräuſche gleichzeitig hören
              <lb/>
            können, ohne daß ſie ſich irgendwie ſtören. </s>
            <s xml:id="echoid-s168" xml:space="preserve">Wie iſt das mög-
              <lb/>
            lich? </s>
            <s xml:id="echoid-s169" xml:space="preserve">Um dies zu verſtehen, betrachten wir noch einmal die
              <lb/>
            Waſſerwellen. </s>
            <s xml:id="echoid-s170" xml:space="preserve">Wenn wir mehrere Steinchen gleichzeitig </s>
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