Need serious help with right hand rule please for magnetic fields

In summary, the magnetic field at the location is negative because the conductor closest to the user is directing the field downwards.
  • #1
pyroknife
613
3
I have attached the drawing.
Why is the magnetic field at the location negative and not positive? When I do the right hand rule I point my thumb in the direction of the current and wrap my fingers around the wire. My fingers pointed up for each wire which should be positive z not negative, but the answer (teacher said it wasn't wrong) is a negative answer.
 

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  • #2
The field around a single conductor consists of circles and concentric circles. For the case in point, for the conductor at y=-6, the circles rise fartherest from you, loop over the top, and sink down between the conductor and you. In the region between the two parallel conductors, the field from the nearest conductor adds to that from the far conductor, being also directed downwards (on the screen). Down is the -z direction. y=-3.8 lies between the two conductors.
 
  • #3
NascentOxygen said:
The field around a single conductor consists of circles and concentric circles. For the case in point, for the conductor at y=-6, the circles rise fartherest from you, loop over the top, and sink down between the conductor and you. In the region between the two parallel conductors, the field from the nearest conductor adds to that from the far conductor, being also directed downwards (on the screen). Down is the -z direction. y=-3.8 lies between the two conductors.

Sorry, that was really hard to understand for me. Is there any way you can phrase that using the right hand rule?
 
  • #4
I think I'm second guessing myself because of this other problem. I attached it again. The arrows indirect the direction of current travel. I need to find the magnetic field due to the wire at point P. Let's consider the left wire the one with the current pointing up. The magnetic field would be IN TO THE PAGE for that right which is negative? The solution manual had a positive answer for that section of the wire. I'm not sure if these are supposed to be magnitudes, if not, I have no idea how it's positive.
 

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  • #5
Your fingers represent the circles, when your whole hand is curled over clutching the conductor. For the conductor in the background, your fingers curl up one side, curl over, and then curl down in the region closest to you.
 
  • #6
pyroknife said:
I have attached the drawing.
Why is the magnetic field at the location negative and not positive? When I do the right hand rule I point my thumb in the direction of the current and wrap my fingers around the wire. My fingers pointed up for each wire which should be positive z not negative, but the answer (teacher said it wasn't wrong) is a negative answer.

Negative how? Specify an orientation with reference to the given coordinate system.

Suggestion: take a close look at the depiction of the coordinate axes. Which directions along those axes are positive and which are negative? The x-axis may be the tricky one...
 
  • #7
gneill said:
Negative how? Specify an orientation with reference to the given coordinate system.

Suggestion: take a close look at the depiction of the coordinate axes. Which directions along those axes are positive and which are negative? The x-axis may be the tricky one...

UGHHH it's b/c of the last problem that I started questioning my method. It turns out I did do it right for my original post and the answer was wrong for the one I attached in my post prior to this one.
 
  • #8
pyroknife said:
The magnetic field would be IN TO THE PAGE for that right which is negative? The solution manual had a positive answer for that section of the wire. I'm not sure if these are supposed to be magnitudes, if not, I have no idea how it's positive.
The field is into the page, but there is no reference here to say which direction is +ve or -ve.


http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html" [Broken]
 
Last edited by a moderator:

1. What is the right hand rule for magnetic fields?

The right hand rule is a method used to determine the direction of a magnetic field. It states that if you point your right thumb in the direction of the current, the curl of your fingers will indicate the direction of the magnetic field.

2. Why is the right hand rule important in understanding magnetic fields?

The right hand rule is important because it allows us to visualize the direction of the magnetic field, which is crucial in understanding its effects on charged particles and other magnetic objects.

3. How do I use the right hand rule to determine the direction of a magnetic field?

To use the right hand rule, point your right thumb in the direction of the current and curl your fingers. The direction in which your fingers curl will indicate the direction of the magnetic field.

4. Can the right hand rule be used for both electric and magnetic fields?

No, the right hand rule is specific to magnetic fields. For electric fields, the left hand rule is used, which is similar but uses the left hand instead.

5. Are there any variations of the right hand rule?

Yes, there are variations of the right hand rule that can be used for different situations. For example, the right hand palm rule is used for solenoids and the right hand grip rule is used for determining the direction of magnetic force on a charged particle.

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