Understanding Magnetic Field Direction from Two Wires at a Distance

AI Thread Summary
The discussion centers on understanding the magnetic field direction created by two wires positioned above and below the x-axis, with one wire coming out of the page and the other going into it. The magnetic field at a distant point X on the x-axis is clarified to point in the positive Y direction, contrary to initial assumptions that it would point along the x-axis. This is explained by the concept that at a significant distance, the wire's vertical position becomes negligible, making it appear as if it is directly on the x-axis. Consequently, the tangent to the field lines at that distance is vertical, resulting in the upward direction of the magnetic field. The explanation emphasizes the importance of distance in determining the effective direction of the magnetic field.
Jstuff
Messages
15
Reaction score
0
You have two wires an equal distance above and below the x-axis the top wire comes out of the page and the bottom wire goes into the page.
Finally, consider point X (not shown in the diagram) located on the x axis very far away in the positive x direction. Which of the vectors best represents the direction of the magnetic field created at point X by wire 1 alone?
Hey guys I am confused on this problem I know the answer is the field will point in the positive Y direction, but I do not understand why.
I thought it would point in the positive x direction because of the right hand rule.
How does the fact that the particles are at a very far distance effect the direction of the magnetic field since the direction of the field would not change it would just become weaker. Right?
 
Physics news on Phys.org
Sketch a set of axes, and mark on it the top wire, and point X far to the right.
 
I've done this. From this and using the right hand rule the magnetic field would point along the x axis. How does the fact that it is very far away on the axis change the direction of the magnetic field?
 
What is the direction of propagation? What direction is the electric field?
The way I understand this, your E field will be oriented with the wire (+Z), and propagation is in the (+X) direction.
 
Well the direction of propagation to my understanding is to the right in the +X direction. However, the answer is that it propagates in the +Y direction from the top wire which I do not understand.
 
This question was posted 6 years ago, but for anyone else confused here's why the the top wire makes a B field that points straight up at a point really far away:

Lets assume you're infinitely far away from the wire. When your that far away, the distance that wire 1 is above the x-axis becomes so small that you can't even see it. Essentially, the wire acts as if its directly on-top of the x-axis. This means that the tangent line on the x-axis infinitely far away is straight up. I hope that makes sense!
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top