large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb_152
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb
English
12904
From the degree of bending the wavelength of the waves can be determined. FROM THE DEGREE OF BENDING THE WAVE LENGTH OF THE WAVES CAN BE DETERMINED
 research that began with the English physicist Charles Glover Barkla (1877-1944). In 1911 he noted that when X rays passed through atoms, some were absorbed and some bounced back. Those that bounced back had a certain ability to penetrate other matter. When the X rays struck atoms of high atomic weight, the X rays that bounced back were particularly penetrating. In fact, each different type of atom seemed associated with reflected X rays of a particular penetrating power, so Barkla called these “characteristic X rays”. In 1913 another English physicist, Henry Gwyn-Jeffreys Moseley (1887-1915), went into the matter more thoroughly. He measured the exact wavelength of the characteristic X rays by reflecting them from certain crystals. In crystals, atoms are arranged in regular order and at known distances from each other. X rays reflecting from (or more accurately, diffracting from) crystals are bent out of their path by the rows of atoms. The longer their waves, the more they are bent. BARCLAY EIGHTEEN SEVENTY SEVEN TO NINETEEN FORTY FOUR IN NINETEEN ELEVEN HE NOTED THAT WHEN X RAYS PASSED THROUGH ATOMS SOME WERE ABSORBED AND SOME BOUNCED BACK THOSE THAT BOUNCED BACK HAD A CERTAIN ABILITY TO PENETRATE OTHER MATTER WHEN THE X RAYS STRUCK ATOMS OF HIGH ATONIC WEIGHT THE X RAYS THAT BOUNCED BACK WERE PARTICULARLY PENETRATING IN FACT EACH DIFFERENT TYPE OF ATOM SEEMED ASSOCIATED WITH REFLECTED X RAYS OF A PARTICULAR PENETRATING POWER SO BARKLA CALLED THESE CHARACTERISTIC X RAYS IN NINETEEN THIRTEEN ANOTHER ENGLISH PHYSICIST HENRY GWEN JEFFREYS MOSELY EIGHTEEN EIGHTY SEVEN NINETEEN FIFTEEN WENT INTO THE MATTER MORE THOROUGHLY HE MEASURED THE EXACT WAVE LENGTH OF THE CHARACTERISTIC X RAYS BY REFLECTING THEM FROM CERTAIN CRYSTALS IN CRYSTALS ATOMS ARE ARRANGED IN REGULAR ORDER AND AT KNOWN DISTANCES FROM EACH OTHER X RAYS REFLECTING FROM OR MORE ACCURATELY DIFFRACTING FROM CRYSTALS ARE BENT OUT OF THEIR PATH BY THE ROWS OF ATOMS THE LONGER THEIR WAVES THE MORE THEY ARE BENT
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