large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb_61
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb
English
12904
If two ends of a wire, making up part of a broken circuit, are brought close to each other with nothing but air between, a spark may leap across the narrowing gap before they actually meet and, while it persists, the current will flow despite the break. IF TWO ENDS OF A WIRE MAKING UP PART OF A BROKEN CIRCUIT ARE BROUGHT CLOSE TO EACH OTHER WITH NOTHING BUT AIR BETWEEN A SPARK MAY LEAP ACROSS THE NARROWING GAP BEFORE THEY ACTUALLY MEET AND WHILE IT PERSISTS THE CURRENT WILL FLOW DESPITE THE BREAK
 negative unit of electricity to itself it would be pulled in the other direction. [Illustration: _Michael Faraday_] The units of electricity were a great deal more difficult to study than the atomic units of matter, and throughout the 19th century they remained elusive. In 1891, though, the Irish physicist George Johnstone Stoney (1826-1911) suggested that the supposed unit of electricity be given a name at least. He called the unit an “electron”. Cathode Rays An electric current flows through a closed circuit of some conducting material, such as metal wires. It starts at one pole of a battery, or of some other electricity generating device, and ends at the other. The two poles are the positive pole or “anode” and the negative pole or “cathode”. If there is a break in the circuit, the current will usually not flow at all. If, however, the break is not a large one, and the current is under a high driving force (which is called the “voltage”), then the current may leap across the break. E IF IT ATTACHED A NEGATIVE UNIT OF ELECTRICITY TO ITSELF IT WOULD BE PULLED IN THE OTHER DIRECTION THE UNITS OF ELECTRICITY WERE A GREAT DEAL MORE DIFFICULT TO STUDY THAN THE ATOMIC UNITS OF MATTER AND THROUGHOUT THE NINETEENTH CENTURY THEY REMAINED ELUSIVE IN EIGHTEEN NINETY ONE THOUGH THE IRISH PHYSICIST GEORGE JOHNSTONE STONEY EIGHTEEN TWENTY SIX NINETEEN ELEVEN SUGGESTED THAT THE SUPPOSED UNIT OF ELECTRICITY BE GIVEN A NAME AT LEAST HE CALLED THE UNIT AN ELECTRON CATHODE RAYS AN ELECTRIC CURRENT FLOWS THROUGH A CLOSED CIRCUIT OF SOME CONDUCTING MATERIAL SUCH AS METAL WIRES IT STARTS AT ONE POLE OF A BATTERY OR OF SOME OTHER ELECTRICITY GENERATING DEVICE AND ENDS AT THE OTHER THE TWO POLES ARE THE POSITIVE POLE OR ANNODE AND THE NEGATIVE POLE OR CATHODE IF THERE IS A BREAK IN THE CIRCUIT THE CURRENT WILL USUALLY NOT FLOW AT ALL IF HOWEVER THE BREAK IS NOT A LARGE ONE AND THE CURRENT IS UNDER A HIGH DRIVING FORCE WHICH IS CALLED THE VOLTAGE THEN THE CURRENT MAY LEAP ACROSS THE BREAK
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