Problems with electromagnetic fields

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CAT 2
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Homework Statement


Copy the following diagram and draw field lines for both magnetic fields. Then, use them to determine the direction of the force acting on the conductor. HINT: Check your answer, using the right - hand rule for the motor principle.
Their diagram:
Diagram of a U-shaped magnet with its N pole in red at top and S pole in grey at bottom, with a circle containing a dot at the centre representing a conductor carrying current out of the page.


2. Relevant equation
n/a

The Attempt at a Solution



My diagram:
Hand-drawn diagram of a horseshoe magnet with the top arm red and labelled N and the bottom arm grey and labelled S, with a circular current-carrying conductor drawn between the poles, shown as a dot with a blue ring, with concentric magnetic field lines circling it and an arrow labelled Force pointing right.



Did I do this correctly? Thanks for any replies![/B]
 
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  • Hand-drawn diagram of a horseshoe magnet with the top arm red and labelled N and the bottom arm grey and labelled S, with a circular current-carrying conductor drawn between the poles, shown as a dot with a blue ring, with concentric magnetic field lines circling it and an arrow labelled Force pointing right.
    IMG_0507.JPG
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  • Diagram of a U-shaped magnet with its N pole in red at top and S pole in grey at bottom, with a circle containing a dot at the centre representing a conductor carrying current out of the page.
    ScreenShot_20180126153453.png
    572 bytes · Views: 732
The B-field diagram isn't very accurate in shape (but the direction is okay), and given that the current is our of the page at us, the qVxB force is in the direction you have drawn. Maybe use Google Images to figure out how to draw a more accurate horseshoe magnet B-field distribution. :smile:
 
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Thanks. So what you are saying is that my circles aren't quite symmetrical, which they should probably be?
 
The field around the wire is fine. The field lines between the poles of the horseshoe magnet will not be circular. They are more like catenaries (stretched rubber bands). If you have iron filings handy, you can delineate the shape of the field and see for yourself.
 
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This is how they taught me, does it mean anything to you about if mine is ok or not?
Diagram of a current-carrying wire (shown as a circle with a cross) between red N and grey S magnet poles, with a force arrow F pointing left; labels say field lines in the same direction cause repulsion and in opposite directions cause attraction.
 
Attachments
  • Diagram of a current-carrying wire (shown as a circle with a cross) between red N and grey S magnet poles, with a force arrow F pointing left; labels say field lines in the same direction cause repulsion and in opposite directions cause attraction.
    ScreenShot_20180126211316.png
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CAT 2 said:
...does it mean anything to you about if mine is ok or not?
Your answer is good. The problem asks you to draw the field lines, but your drawing only needs to be accurate enough to determine the direction of the force. (The field of the permanent magnet will squash the circular lines surrounding the wire to some degree, for example, but that nicety is overkill here.)
 
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