## DLS 2 years ago Find the force on any vertice on a cube because of the rest.All edges have same charge i.e q.

1. DLS

|dw:1364748658135:dw|

2. goformit100

Use coulombs law to find the Required Answer...

3. DLS

thanks

4. electrokid

|dw:1364749278793:dw|

5. electrokid

and ON the surface of cube?

6. DLS

please leave it till here,i want to try it.

7. electrokid

8. DLS

yeah!

9. electrokid

but, your question says, "find the charge"?

10. DLS

that place u assumed as 0,0,0 we have to find there due to rest 7 charges

11. electrokid

find what? force?

12. DLS

yeah!

13. electrokid

no. force at any point on the cube. so, a point P on the cube.

14. DLS

on the edge

15. electrokid

well, off you go then.

16. Mashy

17. DLS

will try in smtym

18. Mashy

and i didn't get the question.. is it to find the electric field at any point on the cube?!

19. DLS

on any edge

20. DLS

all edges have a charge

21. Mashy

there is a difference between vertices and edge you know :P.. all charges are on the VERTICES.. so you need to find electric field at any point on an edge?!

22. DLS

yeah

23. Mashy

its 3d vector analysis man :-/

24. DLS

i suckat it

25. Mashy

its not easy.. you ll have to go brutal math here!

26. Mashy

yea then its piece of cake.. just use i j k form.. !

27. DLS

:/

28. DLS

ata hoga usse yr

29. yrelhan4

@shubhamsrg Who else? :')

30. shubhamsrg

E at any point on the edge ? this can't be the question, please recheck.

31. DLS

on vertice

32. shubhamsrg

|dw:1364751725488:dw| Please circle/mark the position where you want to find the electric field

33. DLS

|dw:1364751777632:dw|

34. shubhamsrg

a charge is kept there? and we have to find E on that? -_-

35. shubhamsrg

hmm, so you want to find the net force acting on the charge.

36. DLS

force

37. yrelhan4

force nikalni hai? lol

38. DLS

yes :/

39. DLS

tume samaj agaya ques :")

40. DLS

@yrelhan4 ata hai??!!

41. yrelhan4

Hmm shayad ho jayega. but abhi nhi kr rha mai. biomolecules kr rha hun.

42. Mashy

Dls.. you seriously need to get your terminologies right :-/.. !!!!

43. yrelhan4

^ best response.

44. electrokid

It does not matter at what corner you find the net force. use the 3D distance vectors. The individual forces would be way easier that way.

45. Mashy

yea... just use position vectors as marked.. and keep your Forces in i j k format.. and then finally add them up and get the magnitude !!

46. electrokid

|dw:1364753502863:dw| and so on

47. electrokid

they'd all have a common factor of $k{q^2\over a^2}$

48. electrokid

just be careful with the signs.. since the forces will be directed along the position vectors but in opposite direction

49. DLS

@shubhamsrg

50. DLS

@electrokid

51. DLS

doubt!

52. electrokid

shoot it.

53. electrokid

@DLS yes?

54. DLS

|dw:1364821535025:dw| Naming them like that for meanwhile. Now what I have is, $\large F_{DA}=\frac{kq^2}{a^2}$ $\large F_{CA}=\frac{kq^2}{\sqrt{2a}^2}cos45^0$ Fca=Fba am i correct with the magnitudes till here?help me determining the directions too! i want to clarify everything tilll this point first.

55. DLS

in the end i meant Fba=Fda* sorry

56. DLS

@electrokid !

57. electrokid

if you mean $F_{CA}=\frac{kq^2}{a\sqrt{2}}$ then you are correct. since all charges are alike, the forces are repulsive and act along the distance vectors from other charge to A.\\ in my above diagram I give two such directions. look it up

58. DLS

yes i meant a root 2 only sorry!

59. DLS

I didn't get the direction part,where will the force act?

60. electrokid

that cos 45 should not be there!

61. DLS

why?:|

62. electrokid

how did you get it to begin with?

63. DLS

IDK when we take components and when not :/ im so confused..

64. DLS

my teacher taught me though,im still messed up with everything.

65. electrokid

"components of a force" you are talking about magnitude. do not include that cos... it'd show up automatically with the vectors.

66. electrokid

when you take vectors like they are, all the things come with it like a package.

67. DLS

okay so dealing with only mag,im correct till here?

68. electrokid

yes. but if you take cos 45, you'd have to take unit vectors.. this increases your work. my advice, do not take that cos45 and simply find the vectors

69. DLS

yes i eliminated that ,rest is correct right? and just that a root 2 thing

70. electrokid

yes. rest seems fine.

71. electrokid

take hintf from the previous picture

72. electrokid

I gotta go now.

73. DLS

please tell me how to do that XZ thing :|

74. DLS

okay,later.