The Naked Scientists
  • Login
  • Register
  • Podcasts
      • The Naked Scientists
      • eLife
      • Naked Genetics
      • Naked Astronomy
      • In short
      • Naked Neuroscience
      • Ask! The Naked Scientists
      • Question of the Week
      • Archive
      • Video
      • SUBSCRIBE to our Podcasts
  • Articles
      • Science News
      • Features
      • Interviews
      • Answers to Science Questions
  • Get Naked
      • Donate
      • Do an Experiment
      • Science Forum
      • Ask a Question
  • About
      • Meet the team
      • Our Sponsors
      • Site Map
      • Contact us

User menu

  • Login
  • Register
  • Home
  • Help
  • Search
  • Tags
  • Member Map
  • Recent Topics
  • Login
  • Register
  1. Naked Science Forum
  2. General Science
  3. General Science
  4. Neutral has 0 voltage, so how does current flow?
« previous next »
  • Print
Pages: [1]   Go Down

Neutral has 0 voltage, so how does current flow?

  • 9 Replies
  • 3319 Views
  • 5 Tags

0 Members and 2 Guests are viewing this topic.

Offline Mel769 (OP)

  • First timers
  • *
  • 3
  • Activity:
    0%
  • Naked Science Forum Newbie
    • View Profile
Neutral has 0 voltage, so how does current flow?
« on: 15/01/2018 15:12:48 »
Im having trouble getting my head round why it is that:-  the neutral in an AC system has 0 volts flowing (in respect to earth), then how does current travel through the neutral cable back to the transformer without any voltage pushing it.

I understand that a voltage is needed to propel the moving electrons (current) around a circuit, from its source, through a load, and back to the source via neutral.

Is it that there really is a voltage in the neutral, but as the neutral is at earth potential, it registers as 0 volts ??
« Last Edit: 15/01/2018 17:08:35 by chris »
Logged
 



Offline Janus

  • Hero Member
  • *****
  • 783
  • Activity:
    13%
  • Thanked: 186 times
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #1 on: 15/01/2018 16:51:05 »
Current flow just requires a voltage difference. As long as the "live" cable has a positive or negative voltage relative to to the neutral cable, current will flow.   Voltage is not an absolute value, but a relative one. There is no such thing as 0 volts in an absolute sense.  0 volts can be wherever we assign it.  We assign it to Earth because it is convenient to do so.
Logged
 
The following users thanked this post: Zer0

Offline chris

  • Naked Science Forum King!
  • ******
  • 7947
  • Activity:
    2.5%
  • Thanked: 273 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Re: Neutral has 0 voltage, so how does current flow?
« Reply #2 on: 15/01/2018 17:13:17 »
@Janus is absolutely right.

The other term for voltage is "potential difference". When a battery or a power station pushes electrons into the positive line it gives them some potential; this may be either a positive or a negative potential; either way, their potential is greater than zero, so their natural tendency is to fall towards zero. So the electrons in the live / positive line try to move towards the neutral line to shed their potential energy. The neutral line is also connected to Earth and the power station, so by returning to the neutral line the electrons are effectively completing the circuit.
Logged
I never forget a face, but in your case I'll make an exception - Groucho Marx - https://www.thenakedscientists.com/
 

Offline wolfekeeper

  • Naked Science Forum King!
  • ******
  • 1384
  • Activity:
    2%
  • Thanked: 55 times
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #3 on: 15/01/2018 18:17:07 »
Basically, electricity is just a bunch of electrons crowding together, trying to get less crowded together, acting as an electrical fluid.

It's similar to water pressure/head. You can define sea level as a 'zero' water pressure, and if something has higher head then it will flow down to sea level, given the chance, or sea level will flow down into it, if it's below sea level.

Electricity is much the same, 'earth' is the level that electrical pressure (i.e. voltage) will flow down to (or will flow FROM earth into something if it has negative volts.)
Logged
 

Offline Mel769 (OP)

  • First timers
  • *
  • 3
  • Activity:
    0%
  • Naked Science Forum Newbie
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #4 on: 15/01/2018 19:48:22 »
Okay thanks guys, the crux of what im getting at is this. Say theres 120v between line and neutral, this potential difference causes current to flow, normally back to the supply transformer through the neutral (which is at earth potential 0V). Okay I get that. So in a live system there is current flowing through the neutral right, so why do i not get a shock if im standing on the ground and i touch the neutral, because there is still current going through it isnt there !!

I suspect it has something to do with the fact that there is no potential difference between the neutral and earth (that im connected to via the ground in this instance); so in that case there is no voltage between neutral and earth, but there is current flowing through the neutral from the live 120v. But i cant feel this 120v if i touch the neutral while im standing on the ground !!! WHY IS THIS PLEASE HELP
Logged
 



Offline wolfekeeper

  • Naked Science Forum King!
  • ******
  • 1384
  • Activity:
    2%
  • Thanked: 55 times
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #5 on: 15/01/2018 21:42:40 »
It's current that hurts you, not voltage. The current isn't flowing through you. If you unplugged the neutral and put yourself in the circuit, you'd die straight away.

But if you just touch neutral and you were earthed, basically, you have a resistance of (say) 1 k ohms, and the neutral wire to the earth has a resistance of a few ohms at most through the substation, so if you touch it, virtually all the current will go down the wire to earth and not through you. But you're not supposed to touch the neutral anyway.
« Last Edit: 15/01/2018 21:44:53 by wolfekeeper »
Logged
 

Offline hamdani yusuf

  • Naked Science Forum King!
  • ******
  • 2023
  • Activity:
    100%
  • Thanked: 58 times
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #6 on: 15/01/2018 21:49:13 »
Quote from: Mel769 on 15/01/2018 19:48:22
Okay thanks guys, the crux of what im getting at is this. Say theres 120v between line and neutral, this potential difference causes current to flow, normally back to the supply transformer through the neutral (which is at earth potential 0V). Okay I get that. So in a live system there is current flowing through the neutral right, so why do i not get a shock if im standing on the ground and i touch the neutral, because there is still current going through it isnt there !!

I suspect it has something to do with the fact that there is no potential difference between the neutral and earth (that im connected to via the ground in this instance); so in that case there is no voltage between neutral and earth, but there is current flowing through the neutral from the live 120v. But i cant feel this 120v if i touch the neutral while im standing on the ground !!! WHY IS THIS PLEASE HELP
the neutral is usually already connected to the earth by the utility providers.
Logged
Unexpected results come from false assumptions.
 
The following users thanked this post: Zer0

Offline syhprum

  • Naked Science Forum King!
  • ******
  • 5093
  • Activity:
    7.5%
  • Thanked: 64 times
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #7 on: 15/01/2018 21:51:13 »
The current flowing back thru the neutral conductor might raise its voltage relative to the Earth by a few volts certainly not enough to give you a shock
Logged
syhprum
 

Offline Colin2B

  • Global Moderator
  • Naked Science Forum King!
  • ********
  • 5272
  • Activity:
    10.5%
  • Thanked: 438 times
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #8 on: 15/01/2018 23:13:39 »
Quote from: Mel769 on 15/01/2018 19:48:22
I suspect it has something to do with the fact that there is no potential difference between the neutral and earth (that im connected to via the ground in this instance);
Yes, it has in fact everything to do with this.

Quote from: Mel769 on 15/01/2018 19:48:22
so in that case there is no voltage between neutral and earth, but there is current flowing through the neutral from the live 120v. But i cant feel this 120v if i touch the neutral while im standing on the ground !!! WHY IS THIS PLEASE HELP
Current will only flow through something if there is a potential difference between 2 points on the object eg you. So your finger touches neutral and your feet touch earth (=neutral) so no current flows through you, just through the wire, so nothing to feel.
What you feel when you touch a live wire eg 120v is not the voltage, but the current flowing through you to earth. If you were suspended in the air with your feet touching the 120v wire you could touch the 120 with your finger and feel no current, feet and finger at same potential.
Logged
and the misguided shall lead the gullible,
the feebleminded have inherited the earth.
 
The following users thanked this post: Zer0



Offline Mel769 (OP)

  • First timers
  • *
  • 3
  • Activity:
    0%
  • Naked Science Forum Newbie
    • View Profile
Re: Neutral has 0 voltage, so how does current flow?
« Reply #9 on: 16/01/2018 00:05:47 »
Thanks iit makes a bit more sense now
Logged
 



  • Print
Pages: [1]   Go Up
« previous next »
Tags: electricity  / neutral  / live  / electromagnetic potential  / electromagnetic force 
 

Similar topics (5)

How many of you here have heard of the topic "Dark Flow?"?

Started by Joe L. OganBoard Physics, Astronomy & Cosmology

Replies: 9
Views: 5165
Last post 20/09/2010 06:11:17
by yor_on
Is time discrete or does it flow like a river, or is it just a "Now" ?

Started by Alan McDougallBoard Physics, Astronomy & Cosmology

Replies: 19
Views: 5220
Last post 16/06/2016 21:09:10
by IAMREALITY
If money is the blood flow of society, are the rich like blood clots?

Started by the5thforceBoard Technology

Replies: 16
Views: 7810
Last post 20/02/2016 01:32:21
by the5thforce
How did time begin to "Flow" out from the Big Bang Singularity?

Started by Alan McDougallBoard Physics, Astronomy & Cosmology

Replies: 6
Views: 3672
Last post 24/05/2016 23:55:12
by Alan McDougall
Why Linear Time "Flow" insists that the universe must be finite?

Started by Alan McDougallBoard Physics, Astronomy & Cosmology

Replies: 20
Views: 5958
Last post 13/07/2016 02:29:33
by Alan McDougall
There was an error while thanking
Thanking...
  • SMF 2.0.15 | SMF © 2017, Simple Machines
    Privacy Policy
    SMFAds for Free Forums
  • Naked Science Forum ©

Page created in 0.166 seconds with 60 queries.

  • Podcasts
  • Articles
  • Get Naked
  • About
  • Contact us
  • Advertise
  • Privacy Policy
  • Subscribe to newsletter
  • We love feedback

Follow us

cambridge_logo_footer.png

©The Naked Scientists® 2000–2017 | The Naked Scientists® and Naked Science® are registered trademarks created by Dr Chris Smith. Information presented on this website is the opinion of the individual contributors and does not reflect the general views of the administrators, editors, moderators, sponsors, Cambridge University or the public at large.