Rank The Magnetic Field At Point P

Question

Shown below are several situations with two wires with currents 2 A flowing out of (.) or into (X) the page. Rank the magnetic field at point P from greatest to least. Count a downward pointing field as negative and upward as positive.

You may assume that each wire or point of interest is separated by the same distance from the adjacent items and that each situation is independent of all others.

 

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A.)  (.) (.) P

 

 

       

B.)  (.) P (X)

 

 

C.)  (.) (X) P

 

 

D.)  (X) P (X)

 

 

E.)  (X) (.) P

 

 

F.)  (X) (X) P

 

 

G.)  (.) P (.)

 

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Greatest 1_ 2_  3_  4_ 5_  6_ 7_ Least

 

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If you could please carefully explain your reasoning, I would appreciate any information to this question!

Answer 1

if you use  right tumb rule ( right tumb at the direction of current - fingers give the direction of magnetic field)

 

x magnetic field on right side field will point down / on left will point up

.  magnetic field on right side field will point up / on left will point down

if p is farther to one of them the magnitude of magnetic field will be less

so if it is adjacent we will show it with ++ or -- and if it is not adjacent we will show it with + or -

 

A) . . P

P is on right so it is pointing up it is adjacent to one of them so we give it ++ and not adjacent to the other one so  we give it + total of +++

 

so 

A) +++

B)++++

C)-

D)0 (they cancel each other ++ and --)

E)+

F)---

G)0

so it is going to be

 

 

B,A,E,D,G,C,F

 

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