## ghazi 3 years ago it is property of charges that like charge repel each other and unlike attract each other ....so how come dipole exists??? why not a positive and a negative charge attract each other , why they stay at a separation??

1. henpen

You could artificially create one:|dw:1346422170948:dw| Then take off the conducting block at the top. A hydrogen atom CAN'T collapse in on itself, and is a dipole.

2. ghazi

didn't get you

3. henpen
4. naveenbabbar

Look at the definition of a dipole. It is an arrangement of two equal and opposite (non interacting) charges separated by a finite separation.

5. naveenbabbar

In case of an ideal dipole the magnitude of charges keeps on increasing and the distance between them is decreasing and still the charges are non interacting. This is an idealisat

6. ghazi

that's the question how come they aren't attracted towards each other ? @naveenbabbar??

7. Jemurray3

If you put real charges in an arrangement like that, they would be. But a dipole like that is just a model to recreate a particular type of electric field. If you'd like, imagine a polar molecule like HCl which can be modeled as a dipole because the electrons spend more time near one atom than the other, imparting essentially a partial positive and partial negative charge to the whole molecule.

8. Jemurray3

Or, alternatively, imagine that you had a metal rod in an electric field, so that charge built up on the ends:|dw:1346430538059:dw|

9. Jemurray3

The field far away from the rod would be the sum of the externally applied E field and the field of an electric dipole, which is basically what the rod becomes in the presence of the external field.

10. Mikael

ghazi All the answers you ve got - not simple enough. And some NOT right. I will give you a hint to a simple (and true) answer: Let's suppose you love a beautiful girl (older then 18 of course) and she loves you passionately. But let's suppose that a cruel world/god/physics teacher/fate glued you to one side of a bridge and glued her to the opposite side. The glue is stronger than you. Surprise ! You cannot merge in passionate embrace. A variant: suppose hundreds of concrete walls separate you and her and you cannot break them - you won't meet neither.

11. Mikael

Hey @ghazi - the way to your "other half" will be revealed by the evil magician-Koala only after you gift him a medal !

12. Jemurray3

Your answer was "they don't touch because they can't". In what way is that helpful at all?

13. Mikael

I will explain: Question of @ghazi was literally "that's the question how come they aren't attracted towards each other ? " MEANING - MOVING to each other. Answer: sometimes obstacles block MOTION of mutually attracting charges. Santa Simplicata

14. ghazi

well thanks for such a nice example @Mikael but i guess i have another explanation but no one agrees to that..and your answer is like violating property of charges

15. Mikael

I see many people typing

16. ghazi

@Mikael may i?

17. Mikael

No ghazi - here is the actual Physical answer. Sorry go first

18. ghazi

sorry this time i won't agree with you @Mikael because your explanation seems a bit pointless

19. Mikael

We will read all the objections - and then refute them ALL together.

20. ghazi

who has refuted....you haven't read mine!!

21. Jemurray3

The fundamental misunderstanding behind the question is the assumption that dipoles are just free charges that are next to each other. That's not how nature works. But the field produced by such an arrangement is very similar to the one that arises from linear polarized molecules, fixed objects in external fields, and many other more physically plausible scenarios. The model |dw:1346433236818:dw| is just a useful simplification.

22. Mikael

Thats what we said - waiting 4 Your objections

23. ghazi

okay

24. Mikael

This is Exactly what I said but I will say it MORE PHYSICALLY EXPLICIT: Charges are NOT ONLY charges, they have other attractive and repulsive forces acting upon them, moreover they cannot move THROUGH solid ISOLATOR MATERIAL

25. ghazi

how come an isolator comes at such a small separation ???

26. Mikael

How small - one molecule is small enough for You ?

27. Mikael

You can frequently meet polarized states with Extra electron on one end and deficient electron on the other end. And still NOT moving and not merging

28. Jemurray3

The point of my response was that the above picture is just a model. You used an example with love and a bridge, so forgive me if I thought your answer was not sufficient to answer the question.

29. Mikael

jemurray I STATED that it is APRELIMINARY HINT ==>> for god's sake - we are supposed to stimulate thought, not give prepackaged answers , man!!!

30. Mikael

I wanted @ghazi to try and ask me "what is this glue?"

31. Mikael

By the way none of you have asked this till NOW ...

32. ghazi

first of all @Mikael don't be stagnant at your though ..listen to what @Jemurray3 is saying.... well i believe charges in dipole do get attracted but there is a limitation of it that is found by potential energy curve |dw:1346433479155:dw| see everything ins this universe wants to be at minimum potential energy and there is certain minimum distance at which potential energy of the system is minimum ....similarly charges do attract each other but after a certain distance that is 'r' if charges comes come closer force of attraction will be converted to repulsion and they both will have a certain minimum distance at which they can stay together ....distance of min potential energy .....please @Mikael read it carefully :)

33. Mikael

This is Potential energy function of WHAT system @ghazi ?

34. ghazi

to charges together ....|dw:1346434024343:dw|

35. Jemurray3

If you could tone down the mind-numbing degree of self-righteousness for a little while, that would be deeply appreciated. I understand that we're not supposed to give prepackaged answers but your response did absolutely nothing to illuminate a possible route to the solution of this CONCEPTUAL misunderstanding.

36. Mikael

Sorry - this E_p is much more specific and does NOT describe any pair of opposite charges. Yes this is dealization of what I had in mind - for a specific case, the case of nucleus and and electron.

37. Jemurray3

I'm not going to turn this into an argument between the two of us. @ghazi that potential energy function is not representative of a dipole. I'm sure @Mikael would be more than happy to explain that it is more like the one you would find in a hydrogen atom. I have to leave for class, but good luck.

38. ghazi

@Vincent-Lyon.Fr??

39. Mikael

Yes @Jemurray3 I think it did, and how? - by prodding him to DEFINE ADDITIONAL forces that might act to block the approaching and merging of the charges. Which @ghazi did actually do - he describes already nuclear forces that prevent a free motion of chrge

40. Mikael

41. ghazi

@jemurray i am not representing dipole....i just said that after certain distance it can't go further , closer

42. Mikael

@ghazi your diagram requires other types of interaction so that the energy goes higher when the charges are "too" close. This happens near a nucleus

43. ghazi

so accordin to you my answer ain't correct??

44. Mikael

If you simply take 2 oppositely charged FREE particles. They will merge exactly as you expected

45. ghazi

no..i didn't say merge..i mean to say that...they will come closer but not beyond that minimum potential energy distance

46. Mikael

And again you are correct -in your diagram, this describes MATTER. Charges inside atoms, quantization of matter NOT free charges. Not Positron+electron in free space

47. Mikael

In free space there will be annihilation - electron and positron WILL merge.

48. ghazi

okay..so what could be the explanation of this??

49. Mikael

Of what? I just told you that these are 2 SEPARATE situations 1 MAtter of Bound charges of opposite charge - no merging there 2 Free space motion where the merge and neutralize.

50. ghazi

in case of dipole ..

51. ghazi

by the way i need to read further...to get a clear explanation and @Mikael photon ain't matter and your point of motion mass was discarded in the question.....i am still struggling with that one

52. Mikael

Dipole is a word. If you mean Molecular Dipole - the charges don't merge because the matter (molecule) between them is not conducting. If you mean Big Macroscopic Laboratory Dipole - aslo in between is a NON-coducting material. Wood, polymer which does not conduct etc.

53. Mikael

C'mon - it sometimes seems that its is futile to teach you. Do you know that a notable part of the mass of our Sun, of other stars are photons ??!

54. ghazi

dipole stands of two poles...

55. ghazi

nothing is futile.....if you can go back then go and check that out ...

56. Mikael

Tell that to the Sun that it's mass is not matter. Tell that to rockets travelling on photon sails - that photons are not matter.

57. ghazi

photon ain't matter..and if you have got any research paper stating photon is matter i would love to read that

58. Mikael

Matter is smething that posseses the following (not for You, not for ME, - the meaning given to it by science, by scientific definition) 1 Localized - major portion of the probability is in limited extension of space 2 Posseses momentum 3 Is counted in quanta (like units) That is THE DEFINITION. Photons satisfy it. By the way there are scores of massless particles - also considered matter.

59. ghazi

okayy let's stop this here..come back to the question...finally i got your answer of my question i would read further and thanks a lot for your time

60. ghazi

i am waiting for the explanation of @Vincent-Lyon.Fr ...please suggest something here

61. Mikael

If you want to discuss interesting and deep questions first read and tell us - what is SCIENTIFIC definition of matter. Thank you in advance. Sincerely, Mikael

62. Mikael

This was of course to @ghazi not anyone else

63. ghazi

@Mikael i will sir....and will let you know everything

64. Vincent-Lyon.Fr

The dipole is just a model of a charge distribution with a total charge equal to zero. It can be created: if you charge a non-conducting rod with positive charges on one end and negative charges on the other. These charges, although they do attract each other will not move towards each other since the rod does not allow it. This would be a macroscopic dipole. In a molecule, any difference in electronegativity will displace the barycentre of negative charges relative to that of the positive charges. What you obtain is best modelled by a dipole: i.e. you can fairly well predict what this molecule will cause and/or what it will undergo using the laws of the ideal dipole. It is the same if you study the motion of the Earth around the Sun. The Earth is best modelled by a point-mass, whereas in other cases, you should describe it as a solid sphere.