Direction of Magnetic Fields

  • #1
PolarBee
14
1

Homework Statement


33.Ex13_v2.jpg

How do I find the direction of the magnetic field at the points?

Homework Equations



Ampere's B = (UI) / (2*pi*r)[/B]


The Attempt at a Solution



I know how the Right hand rule, where your thumb is the direction of the current and your hand wraps the direction of the field, but I'm not sure how it plays in when both the current are opposite.
 

Answers and Replies

  • #2
John Park
193
29
Try applying the right-hand rule to each of the currents separately and combining the results. Remember that fields add as vectors. and that the diagram is symmetric except for the directions of the currents.
 
  • #3
PolarBee
14
1
Try applying the right-hand rule to each of the currents separately and combining the results. Remember that fields add as vectors. and that the diagram is symmetric except for the directions of the currents.
Yes , but aren't they equal and opposite? Wouldn't they just cancel each other?
 
  • #4
John Park
193
29
Have you tried it? Start with point (b). For the upper current your thumb points towards you and your fingers are under your hand. For the lower current your thumb points away from you and your fingers are above your hand . . .
 
  • #5
PolarBee
14
1
Have you tried it? Start with point (b). For the upper current your thumb points towards you and your fingers are under your hand. For the lower current your thumb points away from you and your fingers are above your hand . . .


Oh I see~ I was taking into consideration of of the whole rotation of my hand, so the back of my hand should face wherever the point is? So they're all in the positive x direction?
 
  • #6
John Park
193
29
looks that way to me.
 

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