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Current-carrying wires


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#1 Sriman Dutta

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Posted 22 December 2016 - 06:08 PM

Hi, 

I have this question. Can anyone please explain the answer as I am unwawre of it.

A current I1 carrying wire AB is placed near another long wire CD

carrying current I2. I1 is perpendicular ti I2.  If AB is free to move then it will move :
(A) Towards left (B) Towards Right
© Upwards (D) Downwards
 
 

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#2 Sensei

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Posted 22 December 2016 - 06:19 PM

Do you have two batteries f.e. 1.5V and two wires? Make experiment.. :)

You should see how they move.

Then swap +- polarization, and check again.


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#3 studiot

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Posted 22 December 2016 - 09:13 PM

Do you have two batteries f.e. 1.5V and two wires? Make experiment.. :-)

You should see how they move.

Then swap +- polarization, and check again.

 

 

Said it all, Sensei +1


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#4 swansont

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Posted 22 December 2016 - 09:37 PM

I don't see the correct answer listed
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#5 studiot

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Posted 22 December 2016 - 10:01 PM

I don't see the correct answer listed

 

I don't see a correct question asked either.

 

:-)

 

So I thought sensei's answer pretty imaginative and thoughtful.

Since we don't know where A, B, C or D are or which way L1 or L2 are flowing, and our answer options don't include a no effect option, suck it and see is the only sensible answer.


Edited by studiot, 22 December 2016 - 10:05 PM.

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#6 swansont

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Posted 22 December 2016 - 10:03 PM

I don't see a correct question asked either.
 
:-)
 
So I thought sensei's answer pretty imaginative and thoughtful.
Since we don't know where A, B, C or D are or which way L1 or L2 are flowing, suck it and see is the only sensible answer.

The current and field will be colinear. Cross product is zero for IL x B

Edit: I was not thinking of the proper geometry here
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Minutus cantorum, minutus balorum, minutus carborata descendum pantorum          To go to the fortress of ultimate darkness, click the up arrow ^

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#7 studiot

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Posted 22 December 2016 - 10:07 PM

The current and field will be colinear. Cross product is zero for IL x B

 

Since you posted this whilst I was busy polishing my own post, please see the last version.


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#8 Sriman Dutta

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Posted 23 December 2016 - 05:52 AM

Thanks for the response.

After a while, I realized that for AM, I can use right hand thumb rule to get the direction of magnetic field.

And then, I can use Fleming's left hand rule to get the direction of motion of CD. I did so and got that the wire CD shall move upwards.

Here' the pic.

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#9 swansont

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Posted 23 December 2016 - 12:16 PM

As you've drawn it, the field from CD is into the page on the right and out of the page on the left. The force is not upward for one of those. One could also argue that there is no field at all at AB (ideally, it's zero, but in reality there would be a field)

What if the current is in the other direction? That wasn't specified.

What if the wires are overlapping? No effect from the overlap point, and on opposite sides the force is in opposite directions. The wire would spin. What if they make an "L" shape?
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Minutus cantorum, minutus balorum, minutus carborata descendum pantorum          To go to the fortress of ultimate darkness, click the up arrow ^

I am not a minimum-wage government shill.             Forget it, Jake — it's Crackpottown.

My SFN blog: Swans on Tea                                                           

 

 

                                                                                                                     

 

 





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