
#1
Jan3005, 10:16 AM

P: 53

If you have two parallel wires, each producing a magnetic field, what would the direction of the magentic field be if:
1) Current flowed in the same direction in each wire. 2) Current flowed in opposite direction in each wire. 



#2
Jan3005, 10:20 AM

P: 603

Do you know how a magnetic field around a current carrying wire looks like? What direction are the field lines? Do you know what the force on a currnet carrying wire in a magnetic field is? What is the direction of this force?




#3
Jan3005, 10:23 AM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 38,879

Right hand rule! Point the thumb of your right hand in the direction of current in the wire and your fingers curl around the wire in the direction of the field lines. What happens between the wires when the current is in the same direction? In opposite directions?




#4
Jan3005, 10:25 AM

P: 53

Parallel wires
When the current is in the same directions, the magentic field between the wires are in different directions. I know that the magnitude of magnetic field will decrease relative to if the current was in different directions, but what do I say for direction? I know about the right hand rule, but how do word the direction? Into/out of the page? Away from the wires? I'm not sure.




#5
Jan3005, 10:29 AM

P: 603

Now you know what the magnetic fieldswill look like all you have to know is what is the direction of the force on a wire in a given magnetic field.




#6
Jan3005, 10:30 AM

P: 53

If you know the direction and magnitude of the force on each wire, you use vectors to determine the net direction, right?




#7
Jan3005, 10:44 AM

P: 603

The force on a charged particle in a magnetic field is given by the Lorentz force law: [tex]\vec{F}=q(\vec{v} \times \vec{B})[/tex]
Now current is flowing charge right? And qv is in the direction of the current! With this information, and some knowledge of the cross product (right hand rule, or corkscrew rule), you should be able to figure out the direction of the force. 



#8
Jan3005, 11:22 AM

P: 213

To know the DIRECTION of the force, all U have to do is:
1) use the right hand rule (quoted below). No fancy formulae are required. 2) use this hand rule: right hand open, fingers straight out, thumb to the right. Fingers (except the thumb) point in the direction of the magnetic field, thumb points in the direction of the moving POSITIVE charge (convertional current) and palm of hand points in the direction of the force. 



#9
Jan3005, 04:57 PM

P: 53

But if you don't know the direction of the current, just that they are in the same or different directions on each wire, how do u know the general direction? i.e. in what way will the magnetic fields "interfere" with each other, and what would the net electric field be?




#10
Jan3105, 01:30 AM

P: 603




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