Good evening gentlemen, this was a question from the engineering test. So as always happens when we apply a voltage to a conductor, in this case an iron tube, the tube lets the current pass, precisely because it is a neutral conductor. But if before applying voltage to the tube, we charge it positively or negatively through electrostatic induction, what happens if we apply a voltage? Does the current undergo any changes?

 

How does the tube retain the electrostatic induction before the voltage is applied? AC or DC?, How does it retain a charge?
What has a "neutral conductor" have anything to do with it? How did it become "neutral"?
Is this homework?

 

See how current through tube is affected by charging voltage:

 

In che modo il tubo trattiene l'induzione elettrostatica prima che venga applicata la tensione? AC o DC? Come mantiene la carica?
Cosa c'entra un "conduttore neutro"? Come è diventato "neutro"?
Sono questi i compiti?
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Italiano
Inglese









Carico il tubo con induzione elettrostatica per caricarlo positivamente o negativamente e quindi viene applicata una tensione tramite 2 cavi, CA o CC. Ecco, come si comporta il passaggio di corrente quando il tubo è carico? Scorre più velocemente? si diffonde di più? per neutro intendo che non è carico di energia elettrostatica

 

Scopri come la corrente che attraversa il tubo è influenzata dalla tensione di carica:

View attachment 305060
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no forse il circuito è sbagliato perché non mi sono spiegato bene, nel tuo circuito il tubo viene chiamato resistore, si carica per induzione elettrostatica tramite un van der graaf (e quindi l'induzione non richiede contatto fisico), e quindi, dopo che il tubo è stato caricato elettrostaticamente, viene applicata una tensione CA o CC tramite 2 cavi, quindi come viene influenzato il passaggio di corrente dalle cariche elettrostatiche del tubo? va più veloce? si diffonde meglio? Non lo so

 

no maybe the circuit is wrong because I didn't explain myself well, in your circuit the tube is called a resistor, it charges by electrostatic induction through a van der graaf (and therefore induction does not require physical contact), and then, after the tube has been electrostatically charged, an AC or DC voltage is applied via 2 wires, so how is the passage of current affected by electrostatic charges of the tube? does it go faster? does it spread better? I do not know

OK, capacitance between tube and Earth is 100pF.
Tube is charged to 500 kV voltage.
Then we ON and OFF voltage on tube.
Result is the same:


ADDED:
Exactly as TS asked - "after the tube has been electrostatically charged, an AC or DC voltage is applied via 2 wires"


https://testbook.com/physics/charging-by-induction

 

Why just re-posting the answers in Italian?

 

Why just re-posting the answers in Italian?

I believe he's probably using a translator to post both questions and answers, hence his use of "unorthodox" terms and expressions.

 

How does this question relate to anything in the real world??Iron pipes are not used for conductors except for safety grounding in old buildings. And does "neutral conductor" imply being connected to the mains neutral side???

 

Why just re-posting the answers in Italian?

Yes, I'm Italian and I use Google Translator

 

How does this question relate to anything in the real world??Iron pipes are not used for conductors except for safety grounding in old buildings. And does "neutral conductor" imply being connected to the mains neutral side???

I used the iron tube as an example because it is a conductor and has a good lateral surface but any conductor is fine

 

OK, capacitance between tube and Earth is 100pF.
Tube is charged to 500 kV voltage.
Then we ON and OFF voltage on tube.
Result is the same:

View attachment 305070
ADDED:
Exactly as TS asked - "after the tube has been electrostatically charged, an AC or DC voltage is applied via 2 wires"

View attachment 305073
https://testbook.com/physics/charging-by-induction

I didn't understand the result of your answer, so what happens to the current flowing through the charged conductor?

 

Keep in mind y'all, this is a test question, not a real world situation. And that's all I can add to this thread. Sorry. But it's interesting nonetheless.

 

I didn't understand the result of your answer, so what happens to the current flowing through the charged conductor?

Maybe more detailed picture will help?

____

ADDED. Diagram of non-charged (neutral) tube current:

 

This is an English-only international site. Any further non-English posts may be deleted.

 

Good evening gentlemen, this was a question from the engineering test. So as always happens when we apply a voltage to a conductor, in this case an iron tube, the tube lets the current pass, precisely because it is a neutral conductor. But if before applying voltage to the tube, we charge it positively or negatively through electrostatic induction, what happens if we apply a voltage? Does the current undergo any changes?

Hi,

I am thinking that maybe you should supply a drawing showing exactly what setup you are talking about. That way members would know what you are asking more exactly.

 

CIAO,

Sto pensando che forse dovresti fornire un disegno che mostri esattamente di quale configurazione stai parlando. In questo modo i membri saprebbero cosa stai chiedendo più esattamente.
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no but I think I solved it, I understood from Danko's diagrams

 

no but I think I solved it, I understood from Danko's diagrams

Congrats
He is often very helpful.

 

This seems like a trick question: :" when we apply a voltage to a conductor, in this case an iron tube, the tube lets the current pass, precisely because it is a neutral conductor. But if before applying voltage to the tube, we charge it positively or negatively through electrostatic induction, what happens if we apply a voltage? Does the current undergo any changes? ".
If the pipe is "a neutral conductor", meaning connected to "ground", there will remain no charge after whatever induced voltage ends. So any current will be as determined by Ohms Law: I=V/R.

 

If the pipe is "a neutral conductor", meaning connected to "ground",

I believe the term was used in a different sense due to language differences.