Understanding Magnetic Field Direction and Force Using Right Hand Rule

[planauts]

Homework Statement

[URL]http://ploader.net/files/795e05b46860aa55fc17ce371c14eb99.PNG[/URL]

The Attempt at a Solution

[URL]http://ploader.net/files/574a81d69c34f39fd049610251d0f0bd.GIF[/URL]

Ok so I got the first part of the question. The problem that I am having is the direction of the field lines, which direction would it be? I know I have to use the right hand rule (the curling my fingers one). I am having trouble because there are two currents in opposite direction, so how would I use it? Thanks

I am also having trouble with Part C ii). I don't understand the question.


Thanks

 

[ashishsinghal]

Use the thumb rule two times - one for each current

 

[planauts]

Use the thumb rule two times - one for each current

[URL]http://upload.wikimedia.org/wikipedia/commons/3/3e/Manoderecha.svg[/URL]

[URL]http://upload.wikimedia.org/wikipedia/commons/1/15/LeftHandOutline.png[/URL]

Which one? The first one, right?

But I am still having trouble with it :( There are two currents, the both are opposite, so shouldn't the fields cancel out?

Can you give me more details?

Thanks

 

[ashishsinghal]

Yeah, the first one.
You should see for yourself if they cancel out.
BTW what are the two currents which are opposite. The figure in the question is about a single current through a solenoid. The dots and crosses should not be confused as two wires. They just show the direction of current.

 

[planauts]

Oh, I think I see it. I got really confused with the rule. So it should be towards the left since it is popping out below and popping into the screen above.

Answer: LEFT
Correct?
Thanks for your help :)

 

[planauts]

How would you do the second part?

(ii) A positively charged particle enters the solenoid along its axis. On the diagram, show the path of the particle in the solenoid.

Which axis are they talking about, the positive or negative? And what would happen?

Thanks

 

[ashishsinghal]

yeah, left is right. Now use hand rule for cross product to determine force.