In modern chemistry textbooks, a DC source (battery symbol) is usually shown for cathode ray tube experiments by Thomson and others. Certainly, no battery can provide very high voltages needed for gas discharge experiments. Similarly, Roentgen needed high voltage sources for X-ray experiments. What type of devices did these early physicists use for conducting their experiments? Youtube has several educational videos known as Ruhmkorff coils, but it seems that they are discontinuous sources. Not sure if discontinuous sources were useful for cathode ray experiments or measuring e/m ratio. Is anyone aware of the names of such devices which powered cathode ray tubes used by early physicists? Thanks.
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1$\begingroup$ Wikipedia says "Wimshurst machines were used during the 19th century in physics research. They were also occasionally used to generate high voltage to power the first-generation Crookes X-ray tubes during the first two decades of the 20th century, although Holtz machines and induction coils were more commonly used." $\endgroup$– Rory DaultonCommented Jan 28, 2019 at 0:33
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2 Answers
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In order to obtain a nonpulsating power source some early investigators used Wimshurst or similar static electricity generators, or batteries of many small storage cells.
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$\begingroup$ Thanks all. It is amazing that these simple machines led to amazing landmark discoveries. books.google.com/… $\endgroup$– ACRCommented Jan 28, 2019 at 2:16
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$\begingroup$ Hi -- we usually recommend quoting part of the source, since URLs are finicky and known to disappear just when you need them. $\endgroup$ Commented Jan 28, 2019 at 13:37
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$\begingroup$ And, no surprise: thingiverse has a Wimshurst machine available to D/L and print. $\endgroup$ Commented Jan 28, 2019 at 13:55
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$\begingroup$ As I read more, it seems Wimhurst is also a discontinuous source. How did they do theoretical /precise studies with pulsed sources? $\endgroup$– ACRCommented Jan 28, 2019 at 15:43
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2$\begingroup$ Simply add a few capacitors ('Leyden jars') to the Wimshurst machine to stabilize its voltage (and to increase its lethality). $\endgroup$– jkienCommented Jan 28, 2019 at 15:53
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I believe batteries were used to generate several hundred volts in the early days. They were called Voltaic piles. Davy used a 2000-pair pile made for the Royal Institution in 1808. I believe that would produce a voltage in excess of 2000 volts. Voltaic piles were the source of choice until dynamos and alternators were invented.
