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Help..magnetic fields... watch

1. Omg,i cant understand how they draw lines with the flemmings hand rule
Here is the exercises:

Please draw them for me and also explain them I am self-teaching so mark schemes only say 3 circles at least or something
Help plz
2. For the 1st part:

This would be to do with Flemming's right hand grip rule.
Imagine gripping the wire with your right hand, with your thumb pointing in the direction of the current. Your fingers wrap around the wire in the direction of the magnetic field.
3. (Original post by starofale)
For the 1st part:

This would be to do with Flemming's right hand grip rule.
Imagine gripping the wire with your right hand, with your thumb pointing in the direction of the current. Your fingers wrap around the wire in the direction of the magnetic field.
So what about that circle with dot. We ignore it in the first part ?
4. i think the circle with the dot is the cross section of the wire seen from above so the top of the wire is the north pole? We did it in physics but have a teacher who does not explain anything well at all
5. but it says magnetic field
6. Guys i have the day next tomorrow exam,so i need urgent help !
7. if the top is the north pole, the field must go from north to south? Im not sure about the next part though
8. the circle with the dot in is definatly the mag field. I would just ignore it though im probably wrong
9. in the second part the currents seem to have to be parallel... does that maybe mean the currents are flowing in the same direction which is why they move away from each other because the pole are repelling? This is so confusing
10. (Original post by Neofytos)
So what about that circle with dot. We ignore it in the first part ?
from our notes if the circle has a dot in it it's the north pole, if the circle has a '+' sign in it it's the south pole
11. This is about the electromagnetic field which is present when a current is passed through a wire.
In the first part of the question, where it asks to draw the field, the picture it asks you to draw them onto is a picture of the end of the wire, with the current coming out of the page towards you. ( Think of it like an arrow in the direction of current - you see the tip - a dot it is coming towards you. See the feathers - a cross - it is going away, into the page. ) In this case, the right hand screw rule can be used, and it shows the field lines are in circles around the wire.
For the second part of the question, the right hand rule can be used, hold thumb, first finger and middle finger perpendicualr to each other, then remember First finger for the Field direction, seCond finger Current, thuMb Movement. All the rest of the things it asks can then be worked out from this I think.
12. (Original post by 2pepper2)
This is about the electromagnetic field which is present when a current is passed through a wire.
In the first part of the question, where it asks to draw the field, the picture it asks you to draw them onto is a picture of the end of the wire, with the current coming out of the page towards you. ( Think of it like an arrow in the direction of current - you see the tip - a dot it is coming towards you. See the feathers - a cross - it is going away, into the page. ) In this case, the right hand screw rule can be used, and it shows the field lines are in circles around the wire.
For the second part of the question, the right hand rule can be used, hold thumb, first finger and middle finger perpendicualr to each other, then remember First finger for the Field direction, seCond finger Current, thuMb Movement. All the rest of the things it asks can then be worked out from this I think.
For 2nd part..whats the field direction ?

About first is it like this ?

Also about secnd the ratio how much is it and why ?
13. (Original post by Neofytos)
For 2nd part..whats the field direction ?

About first is it like this ?

Also about secnd the ratio how much is it and why ?
Newton's third law... if the force exerted by the wire with current I exerts a force F on the wire with current 2I, therefore, what can you say about the force the wire w/ current 2I exerts on wire with current I?
14. same?
15. Anyone ? How do we know the field direction in part b ?
16. You already know this from part 1. Remember the force is there because of the interaction of the fields from both wires. In this case, using the right hand screw rule, you know that the field from wire Y is going into the page at wire Z. You can then use right hand rule to find direction of current.
You can the use the right hand screw rule on wire Z to find the direction of the force in wire Y.
17. (Original post by 2pepper2)
You already know this from part 1. Remember the force is there because of the interaction of the fields from both wires. In this case, using the right hand screw rule, you know that the field from wire Y is going into the page at wire Z. You can then use right hand rule to find direction of current.
You can the use the right hand screw rule on wire Z to find the direction of the force in wire Y.
Thanks a lot,now i get it

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