Electricity Basics: What is Charge?

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Discussion Overview

The discussion centers around the concept of "charge" in electricity, exploring its definition, properties, and how it can be understood or explained. Participants share various perspectives on the nature of charge, its relation to other physical concepts like mass, and the challenges of conveying its meaning to someone unfamiliar with the topic.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that charge is an intrinsic property of particles that interacts with the electromagnetic field, similar to how mass is defined by its effects.
  • Others argue that understanding charge requires a focus on its behavior rather than a definitive explanation of what it is, noting that fundamental properties often resist clear definitions.
  • A participant mentions the importance of demonstrations, such as the "sticky-tape" experiment, to help visualize charge.
  • Some express that it is difficult to explain charge without addressing misconceptions about related concepts like mass, suggesting that understanding one may aid in grasping the other.
  • There is a viewpoint that acknowledges the limits of current understanding, stating that nobody truly knows what charge is at a fundamental level, only how it behaves.
  • Another participant emphasizes that while charge is understood in terms of its effects, it could potentially be a byproduct of more fundamental properties that are yet to be discovered.
  • Experiential learning, such as observing charge in motion (e.g., lightning or in laboratory experiments), is suggested as a way to clarify the concept.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of charge, with no consensus reached on a definitive explanation. Some agree on the importance of understanding behavior over definition, while others highlight the uncertainty surrounding the fundamental nature of charge.

Contextual Notes

Participants note that discussions about charge often lead to deeper questions about fundamental concepts in physics, such as mass and energy, which may not have clear answers. The conversation reflects the complexity and ambiguity inherent in defining basic physical properties.

Who May Find This Useful

This discussion may be of interest to individuals exploring foundational concepts in physics, particularly those grappling with the definitions and implications of charge, mass, and other related properties.

Pengwuino
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I was trying to explain a little bit about electricity to my friend and i came across a problem. What exactly is "charge". I know you can say that a proton has this charge or an electron has this charge and we know what they do... but what exactly IS a charge?
 
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It's the intrinsic property of a particle that interacts with the electromagnetic field.

How would you answer 'what is mass'?

Most people would answer 'it's what makes things heavy'. What does heavy mean? a) resists acceleration (inertia); b) moves towards the source of a gravitational field (gravity).

Similarly, 'charge' is what makes things resist acceleration (radiation force), and move towards or away from the source of an electric field, and move perpendicular to a magnetic field.

Like Batman said, it's our actions that define what we are.
 
My friend is having a hard time understanding because he just "cant understand it without seeing it and thinking 'this is a charge'" (after picking up a case of cds and scissors) and i tried to explain it and i also realized I didn't know how to go beyond "its the properties of a particle that...". Sounds like i need to watch more Batman before i go into my next physics courses :D
 
Show him some lightning. That's charge in motion.
 
Well what you see is light though so it doesn't really count as an instance where you literally "see" charges.
 
Pengwuino said:
... thinking 'this is a charge'" (after picking up a case of cds and scissors)

Maybe that is the problem. I recall reading a paper (in AJP?) on semantics in physics which suggests that "mass" and "charge" are properties (in accord with El Hombre Invisible) like "color" is a property. [I'm not completely sure... so don't quote me.] So, it's not "a charge" but "an object with charge", etc.

While this alone might not help you explain "charge", maybe you need a demo... like the "sticky-tape" demo (e.g. http://www.amasci.com/emotor/sticky.html .. it seems on that site, there is another page "WHAT IS "ELECTRIC CHARGE?" http://www.amasci.com/elect/charge1.html which I haven't read thoroughly).
 
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Pengwuino said:
My friend is having a hard time understanding because he just "cant understand it without seeing it and thinking 'this is a charge'" (after picking up a case of cds and scissors) and i tried to explain it and i also realized I didn't know how to go beyond "its the properties of a particle that...". Sounds like i need to watch more Batman before i go into my next physics courses :D
Probably your best bet is to first undo his idea of what something more simple like 'mass' is. If you can convince him that you can really only define what mass is by what it does (inertia, gravity) then you'll get him into the right state of mind. After all - you can't 'see' mass either. Try undoing some of his preconceptions in this kind of area, such as that mass is resposible for contact forces (i.e. what stops us walking through walls). When you can get him to understand mass, then apply the same logic to charge, again by explaining how it behaves rather than where it comes from. I think I'd find that heplful at that level.
 
El Hombre Invisible said:
Probably your best bet is to first undo his idea of what something more simple like 'mass' is. If you can convince him that you can really only define what mass is by what it does (inertia, gravity) then you'll get him into the right state of mind. After all - you can't 'see' mass either. Try undoing some of his preconceptions in this kind of area, such as that mass is resposible for contact forces (i.e. what stops us walking through walls). When you can get him to understand mass, then apply the same logic to charge, again by explaining how it behaves rather than where it comes from. I think I'd find that heplful at that level.

Well i coulnd't even explain special relativity to him without him doing the old 'no no that's wrong... look at the biological clocks in this situation'.
 
I would also suggest that you go with El Hombre Invisible suggestion. And also you can be a little honest and simply say that nobody really knows what charge is! The truth is once we get down to really fundamental ideas then we can't explain what it is but instead how it behaves. I mean if you think about anything deep enough we will not know what it is because we will end with questions like what really is interia or mass. So it is futile to explain what it is sometimes until some breakthrough leads to an understanding of something else that causes charge and then we won't know what that is but just how it behaves. So tell your friend to snap out of his/her current state of not be able to grasp ideas simply because we don't know what they are.
 
  • #10
We know a hell of a lot about charge, we know exactly how it behaves and what effect it exerts on other objects around it.

You can't describe fundamental properties in terms of more fundamental properties (obviously since they wouldn't be fundamental otherwise). Point is, we know what how it behaves and how it influences the world around it, and that is all we really need to know.

Of course, it could emerge in the future that charge is not fundamental, but rather a by product of a more fundamental property, in which case we could describe charge in terms of something more fundamental.

But until then, I'm happy to describe charge as a fundamental property of elementary particles.

Claude.
 
  • #11
Antiphon said:
Show him some lightning. That's charge in motion.

I was having similar confusions about charge,but when i did Helmholtz experiment in lab which aims at finding e/m,all my confusions disappeared after seeing electrons in motion!
 
  • #12
what is charge?
what is mass?
what is energy?
that are questions that u can't answer. mass is thought to be answered by the higgs particle but that's a theory yet.
 
  • #13
Pengwuino said:
My friend is having a hard time understanding because he just "cant understand it without seeing it and thinking 'this is a charge'" (after picking up a case of cds and scissors) and i tried to explain it and i also realized I didn't know how to go beyond "its the properties of a particle that...". Sounds like i need to watch more Batman before i go into my next physics courses :D

Well, you can start by asking your friend if he believes in the existence of air, even if he can't see it.

If he doesn't believe in air, a few experiments come to mind, but unfortunately they are unsafe, so I won't post them.

Assuming you get past the "beliving in air" problem, point out that you can detect charge with a variety of instruments, the gold-leaf electroscope would probably be the best choice as it is fairly simple and detects static charges.
 
  • #14
Zelos said:
what is charge?
what is mass?
what is energy?
that are questions that u can't answer. mass is thought to be answered by the higgs particle but that's a theory yet.

There all anthropic labels used to define characteristics :biggrin:
 

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