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moenste
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Homework Statement
The diagram shows a uniform magnetic flux density B in the plane of the paper. Q and R mark the points where two long, straight and parallel wires carry the same current, I, in the same direction and perpendicular to the paper. The line through QR is at right angles to the direction of B.
P is a point where the resultant magnetic flux density is zero, i. e. it is a neutral point. P is closer to R than to Q.
(a) Explain whether the direction of the current I is into or out of the paper and sketch a diagram which shows the directions of the different magnetic flux densities present at P.
(b) If I is increased slightly, will the neutral point at P move towards Q or towards R?
(c) There is a second neutral point on the line through QR. State whether it is to the left of Q, between Q and R or to the right of R.
2. The attempt at a solution
(a) I have no idea how to find the direction of current. Boths wires are parallel and have one direction. How to find it?
This is how I see it.
(b) Nothing will change, right? Why would it?
Or maybe if the current is increased, the point will move towards R, towards the stronger wire? The P point is closer to R so I assume the field is stronger there. And we increase I, R the current at R will attract the P point even more. Maybe like this?
(c) Since both of the wires are the same, I would say that another point will be between Q and R, at the same distance from Q as P is from R. But not sure whether this is right.
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