Discovery of Electrons: A Stroke of Luck?

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Discussion Overview

The discussion revolves around the historical context of the discovery of electrons and the terminology associated with electrical components, specifically the terms cathode and anode. Participants explore how early scientists assigned positive and negative charges and the implications of these conventions in the understanding of electricity.

Discussion Character

  • Historical
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question how batteries were invented without knowledge of electrons and protons, suggesting it may have been by chance.
  • Others argue that a microscopic theory is not always necessary to explain macroscopic phenomena, citing historical developments in electricity from the 16th century onwards.
  • There is a discussion about the definitions of cathode and anode, with some noting that these terms were used before the discovery of electrons, raising questions about their original meanings.
  • One participant highlights that the cathode is defined as the electrode where reduction occurs, and that definitions can vary between contexts, such as batteries and electrolytic cells.
  • Another participant points out that the assignment of positive and negative terminals was arbitrary and based on observed effects rather than an understanding of the underlying mechanisms.
  • Some participants reference Benjamin Franklin's contributions to the understanding of electricity and the assignment of charge conventions, noting that these were established before the electron was discovered.

Areas of Agreement / Disagreement

Participants express differing views on the historical assignment of charge and the definitions of electrical terms. There is no consensus on the implications of these conventions or their historical accuracy.

Contextual Notes

The discussion includes references to historical terminology and conventions that may not align with modern definitions, highlighting the evolution of understanding in the field of electricity.

jd12345
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I was studying the cathode ray experiment on how electron was discovered and the experiment uses battery for voltage.
How did the people invent battery without knowing electrons and protons ( by chance?)

And how was the name cathode and anode given without knowing which is positive and which is the negative terminal?
 
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jd12345 said:
How did the people invent battery without knowing electrons and protons ( by chance?)

How did people invent drinking without knowing that water consists of molecules of H2O?
Seriously, you hardly ever need a microscopic theory to explain and exploit macroscopic phenomena.
I think you will find on the net (not to mention books) plenty of good accounts on the history of electricity. Just some key words: People were building already in the 16th century electrization machines. Benjamin Franklin coined the terms positive and negative electricity and could show their relation. Batteries were invented by Galvani and Volta.
 
Ok, stupid question ( didnt realize )
another question : Cathode is defined as the electrode where electrons enter. But the terms cathode and anode were used before discovery of electron so what did cathode and anode mean then?
 
jd12345 said:
Ok, stupid question ( didnt realize )
another question : Cathode is defined as the electrode where electrons enter.

No, and even less in a chemical context. The cathode is where the reduction takes place. I.e. in a battery it is the positive pole, in an electrolytic cell it is the negative one.
So your definition only holds true for an electrolytic cell.
In electrotechnics it is (or was) defined in terms of the technical direction of the current which goes from plus to minus.
The electron is really not so important in the definition of current. E.g. in an electrolyte, current is carried by ions and, especially in case of hydronium ions, positive charge carriers may dominate. And finally in a condensator, there may be no charge carriers at all, nevertheless a displacement current can flow.
 
okay - actually I'm learning(researching) about history of electricity - so just a question i mind which is troubling me:- How did they assign positive and negative terminals?

example :- In a galvanic cell zinc anode is negative and copper cathode is positive. We know this now because we know electrons flow from zinc to copper.

But how did they assign a direction to current and on what basis did they distinguish positive and negative charge?
 
At random. The named it this way to describe observed effects, not knowing the mechanism behind. They failed, which is a reason why electrons flow in the opposite direction to the current.

Many conventions start this way. You have to use some convention, so you select the one that suits you. Everyone else follows. Or, there are competing conventions and sooner or later one prevails, sometimes for no other reason but just because the person using one convention is more liked by people than the other.
 
jd12345 said:
example :- In a galvanic cell zinc anode is negative and copper cathode is positive. We know this now because we know electrons flow from zinc to copper.

No, we did know this long before we knew anything about electrons.
Before B. Franklin one distinguished "glassy" electricity from "resinous" electricity (I translated these terms from German, I am not sure whether it coincides with Franklins terminology) as glas rods tend to charge up positively and resins (like amber = greek "elektron") negatively. Franklin recognized that there is only one sort of electricity and created a "one fluid" theory of electricity.
He assigned "plus" to the glassy electrically charged and minus to the resinous charged bodies.
He also did chose the convention that electric current flows from plus to minus.
It is relatively easy to show that e.g. a charged glass rod will be attracted to the zinc pole of a galvanic cell, so the pole must be negatively charged. Even easier is to measure the direction of the resultant current via its magnetic effects.
 
thank you guys
 

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