Why do we consider induction a way of charging?

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    Charging Induction
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Discussion Overview

The discussion revolves around the concept of charging by induction, specifically addressing how an uncharged object can become charged when influenced by a nearby charged object. Participants explore the mechanics of charge induction, the implications of net charge, and the conditions under which an object can be considered charged.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that while charges of opposite sign are induced on the surface of an uncharged object, the total charge remains zero, leading to the question of why this process is termed "charging" if the net charge does not change.
  • Another participant introduces the idea of inducing a charge difference on a long rod, suggesting that cutting the rod in half after induction results in two separate objects, each with a net charge, thus illustrating the concept of charging by induction.
  • A follow-up question asks whether an object can be considered charged if it is not cut, emphasizing the importance of net charge remaining zero if the object remains intact.
  • A different perspective is offered, explaining that touching the conductor while it is near a charged object allows electrons to move, resulting in a net charge on the conductor without needing to cut it in half.
  • Participants discuss the role of potential in explaining the charging process, indicating that a more nuanced understanding may be necessary.

Areas of Agreement / Disagreement

Participants express differing views on whether an object can be considered charged if it retains a net charge of zero. Some argue that cutting the object is necessary for it to be charged, while others suggest that touching the object can also result in a net charge. The discussion remains unresolved with multiple competing views present.

Contextual Notes

Participants highlight the dependence on definitions of charge and the conditions under which charge induction occurs. There are unresolved aspects regarding the mechanics of charge movement and the implications of potential in the charging process.

explainplease
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I get that by getting a charged object near an uncharged one, charges of the opposite sign are induced on the surface, but, since the total charge of the whole object is still zero (because electrons move inside the conductor and can't escape because surroundings insulate it) , the object as a whole can't be considered charged, only the surface, so why would we call induction a means of charging while the net charge of the object doesn't change?
 
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explainplease said:
I get that by getting a charged object near an uncharged one, charges of the opposite sign are induced on the surface, but, since the total charge of the whole object is still zero (because electrons move inside the conductor and can't escape because surroundings insulate it) , the object as a whole can't be considered charged, only the surface, so why would we call induction a means of charging while the net charge of the object doesn't change?

Imagine inducing a charge difference on a long rod. One end is positive, the other negative. Now cut the rod in half. Now you have two separate objects, each with a net charge.

This is what we mean by "charging by induction". You induce a charge across an object, then cut the connection between the charged ends.
 
axemaster said:
Imagine inducing a charge difference on a long rod. One end is positive, the other negative. Now cut the rod in half. Now you have two separate objects, each with a net charge.

This is what we mean by "charging by induction". You induce a charge across an object, then cut the connection between the charged ends.

so if i didn't cut the object, then i haven't charged it because the net charge would remain zero right?

Thank you :)
 
I'd add to axemaster's reply that you don't necessarily have to cut the object to be charged in half, to isolate net charge. Suppose the object to be charged is a conductor, and that you hold it near a negatively charged object, N. Then free electrons in the conductor will be repelled towards the parts of the conductor furthest from N. If you now TOUCH the object, electrons can be repelled even further from N - on to YOU, and probably via you to the ground. The conductor now has a positive charge. Let go of it, THEN remove N, and the conductor will be left with an overall positive charge.

The same works, making necessary changes to the explanation, for charging a conductor negatively using an external positive object.

A better explanation of what goes on in each case uses the idea of potential.
 

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