What the flux?

Discussion in 'Physics' started by BR-549, Dec 6, 2014.

1. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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Three flux questions.

1. I have a 36" dia. sphere charged with 10 coulombs. I am standing 10 foot away with a certain number of field lines hitting me due to inverse square law.
Now, without anything changing positions......the sphere is reduced to 1/32" dia. Same 10 coulombs........Does the number of flux lines hitting me change?

2. Change sphere to 36" plate(perpendicular) and repeat. Does number of flux lines change?

3. I invented a variable area capacitor. I put a steady 10 coulomb charge on the input plate.
If I vary the area between the plates........Will my output voltage vary with area?

The charge on the sphere, plate and cap input remains constant.

Aug 27, 2009
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3. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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You may use any theory or mechanism you wish, but the field or flux must be a real physical entity, emitted from and connected to the source evenly in a repulsive manor, i.e., the field or flux is self spreading. Fields or flux is self repulsive.

Yes, empty space between objects and field or flux lines. And the field or flux does not effect the properties of space, except to occupy it.

Would the output current change with varying area?

Last edited: Dec 6, 2014
4. nsaspook AAC Fanatic!

Aug 27, 2009
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1.
The excess charge is always seen from the center of the sphere so what do you think?

If you have a JAVA enabled browser try some of these applets to visualize.

See:
Electricity and Magnetism: Statics

Last edited: Dec 6, 2014
5. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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I have a 36" square plate.
I have a 1 foot dia. sphere centered 10' away on the left side. 10 coulomb of + charge.
I have a 1/400 foot dia. sphere centered 10' away on the right side. 10 coulomb of - charge.
What is the charge on the plate?

6. studiot AAC Fanatic!

Nov 9, 2007
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I have absolutely no idea what you mean by this so please rephrase in conventional terms.

The conventional flux through a sphere of set radius depends only on the total charge contained and the radius, not the internal distribution of that charge, so if you hold the radius and total charge constant the flux will not change.

7. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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Does the flux change with a change in radius of sphere?
Don't change the distance between sphere and me.
Don't change charge amount(coulomb).
Just shrink sphere size.
Does amount of flux hitting me change?

8. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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studiot....pardon me, I was trying to oblige everyone.
Was it the "any theory or mechanism" part?
Or something else?

9. studiot AAC Fanatic!

Nov 9, 2007
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Perhaps I should not have mentioned spheres at all. I was really trying to avoid maths for you.

But yes it was something else since the flux lines I am familiar with start at the ball of charge and carry on out to infinity, they do not end as you have specified. Nor do I know what you mean by self repulsive or self spreading.

But yes if the charge is constrained to a ball of any size within your standing distance from its centre, the field will be evenly spread and the same as if all the charge was concentrated at the centre of the ball.

So if you are standing 10 feet away then it doesn't matter if the charge is spread out over a ball of half an inch radius or six inches or six feet radius, you will experience the same flux where you stand.

Remember also that there is a difference between flux and flux density and be sure of which one you actually want.

Last edited: Dec 6, 2014
10. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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I believe my questions were very clear and concise if you would review closely.

My questions require a yes or a no. No more.

What other property does electric flux have other than density and polarity?

Can field lines have different potentials?

Is there a difference between one 10 volt field line and one, 1 volt field line?

When you back off from a charge, does the voltage drop because the strength of the lines drops off with distance?........Or does the strength stay constant with each line and ONLY the number of lines decrease?

Field lines are polarized. Therefore they are repulsive. This is what causes the field to be evenly spread. For the ones who are more confused, isotropic.

I don't recall saying a field line ended.

I don't understand the confusion. These are simple basic questions.

Most questions with charge involve distance and charge magnitude.

I decided to set these constant and change surface area(SIZE) of source.

We don't change this very often. Or we don't think about it. Maybe some think there is no need.

With the extensive and varied experience, training, education and generational differences on this site, what better place to ask?

No one has to justify there answers.

I am just curious if anyone thinks this matters?

Would a variable size, constant charge source effect flux at a distance?

11. nsaspook AAC Fanatic!

Aug 27, 2009
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I think you are mixing the archaic Lines of Force concept and vector Field Lines. Is this mainly a question about the 'physical reality' of field lines as normally seen in modern classic EM visual diagrams.
IMO modern physics sees the electric and magnetic fields as real (significance/existence) but the lines are a mathematical representation of the vector field.

Lines of Force: http://en.wikipedia.org/wiki/Line_of_force
Field Lines: http://en.wikipedia.org/wiki/Field_line

12. studiot AAC Fanatic!

Nov 9, 2007
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And you received simple basic answers and genuine offers of help, which you scorned.

There is nothing more to be said.

13. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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Really? I am sorry if I hurt your feelings.
Does my confusion on anything in nature change the answers to my questions?
Is any part of my question invalid or break any law?

Do you need any other information on the setup?

I am not trying to intimidate or trick anybody.

I have been educated with the same theories and knowledge as you.

So please.....give me a yes or no on those three questions.

I promise I wont hold you to them.

14. nsaspook AAC Fanatic!

Aug 27, 2009
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If you troll, you will be treated like a troll.

15. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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Now, now nsaspook, you better be nice. You know what's coming in a few days.
You'll be put on the naughty list.

16. MrAl Distinguished Member

Jun 17, 2014
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Hi,

I think the problem here is that you refer to "field lines" and then later "flux lines".
If you mean "field lines" in both cases, then the answer is "YES".

17. studiot AAC Fanatic!

Nov 9, 2007
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Mr Al, you might like to review post#16

18. nsaspook AAC Fanatic!

Aug 27, 2009
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That would be Counterfactual.

19. BR-549 Thread Starter Distinguished Member

Sep 22, 2013
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MrAl, thank you.
I will mark you down as a yes on all 3 questions. And a yes on the fourth too....the current.
I had no idea and I apologize for the confusion.....please forgive me.
Field lines are fine.

Flux would be number of lines per area or the number hitting me.

20. MrAl Distinguished Member

Jun 17, 2014
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Hi,

Weren't we assuming that the 'distance' from the point source is always the same?
Maybe i misinterpreted.