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Compass Between two wires

  • Thread starter Samurai44
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  • #1
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Homework Statement


two wires are parallel to each other,carries current of same magnitude, and the distance between them is 10cm ,, wire A carries current out of the page ,, Wire B carries current into the page ..... A compass is placed at 4 cm from wire A .. Where does the needle point ?

I also would like to know where does the needle will point if the two wires carries same current direction

Homework Equations


-
same current direction - Attraction
opposite current direction - Repulsion

The Attempt at a Solution


I drew the magnetic field around each wire(Wire A-Anticlockwise ... Wire B-Clock wise) , but since the field is circular around a straight wire , so I couldnt know where it will point exactly .
 

Answers and Replies

  • #2
gneill
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I drew the magnetic field around each wire(Wire A-Anticlockwise ... Wire B-Clock wise) , but since the field is circular around a straight wire , so I couldnt know where it will point exactly .
It will be tangent to the circle at any location around the circle.
 
  • #3
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It will be tangent to the circle at any location around the circle.
so the other wire wont affect the direction of the needle unless the compass was at mid point ?
 
  • #4
gneill
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so the other wire wont affect the direction of the needle unless the compass was at mid point ?
No, the fields from both wires will sum at any given location (superposition principle). Pick a location and sketch the circles centered on each wire that pass though that point. Sketch in the field vector at that point for each wire. Sum the vectors.
 
  • #5
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No, the fields from both wires will sum at any given location (superposition principle). Pick a location and sketch the circles centered on each wire that pass though that point. Sketch in the field vector at that point for each wire. Sum the vectors.
alright thanks
 

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