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1. ### Basic exercise of path integral

Thanks so much for the answer. Now for me is clear :D .
2. ### Basic exercise of path integral

Because from the definition, the integration limits are the initial and the final points. From path c the particle starts from the point (0,1) and ends at the point(1,0). Also, the ##\vec{dr}## is the direction of the displacement, in that case, would be negative (##\vec{dr} = -dx \hat{i}##).
3. ### Basic exercise of path integral

So how would you set up the integral of this path?, $$W = \int_{1}^{0} \vec{F}\cdot d\vec{r} =\int_{1}^{0} (xy \hat{i} +y^2\hat{j })\cdot (dx \hat{i}) = \int_{1}^{0} xy dx$$ For me it is not totally clear yet the reason.
4. ### Basic exercise of path integral

Thanks for the answers. It is clear to me that the integral must be negative since the force is opposite to the displacement. However, the path integral is defined as $$W = \int_{a}^{b} \vec{F}\cdot d\vec{r}$$ where a and b refer to the start and end points, respectively. In this example a...
5. ### Basic exercise of path integral

In the book it is mentioned that, in path c, the line integral would be: $$\int \vec{F}\cdot \vec{dr} = A \int_{1}^{0}xy dx = A\int_1^0 x dx = -\dfrac{A}{2}$$. but I think that dx is negative in that case, the result would be positive, right?
6. ### A Doubt about a time convolution master equation

I study of interaction between a system with a reservoir considering a weak coupling between them. I consider a bosonic bath, the initial state are separable and the operator of interaction between the system and bath is linear in the displacements of the oscillators. . In the book "Quantum...
7. ### Doubt about a unit vector in toroidal coordinates

The system considers a torus that has a wire wrapped around it, through which a current flows. In this way, a field originates in the phi direction. The direction of current is "theta" in the spherical coordinate system but in toroidal system, in several book shows that the electrical current...
8. ### Boundary of an inequality

in this case $$(x-1)^2 \le (a+1)^2$$ and $$(x-1/2)^2 \le (a+1/2)^2$$
9. ### Boundary of an inequality

Homework Statement I would like to know how the boundary of the inequality change when the origin of the coordinate system changes. Homework Equations The original inequality is[/B] $$r_0 \le x^2+y^2+z^2 \le R^2$$ I would like to know the boundary of the following term, considering the...
10. ### Quantum Pair production QED

It's my first quantum field theory course.
11. ### Quantum Pair production QED

Homework Statement In a few more months I have to present a report about pair production in quantum electrodynamics, using Feynman diagrams. I have been using the QFT Schwartz book, I find it a bit advanced for my level, could someone recommend me a book to study this phenomenon?. Thank you...
12. ### Capacitance capacitor parallel plate with dielectric (Gauss)

Homework Statement I have an elementary doubt with the calculation of the capacitance of a capacitor of parallel plates that has a dielectric in the middle. https://ibb.co/b0W4BQ Homework Equations ∫D⋅ds=Q D=E+γP C=Q/V The Attempt at a Solution Suppose the top plate has a positive charge...
13. ### Particle moving inside an inverted cone - Lagrangian

Hi, This restriction is correct? May be alpha= constant? thanks
14. ### Classical Companion book for Electrodynamics by Jackson

I am studying electrodynamics, in a few more months I have the qualification exam. The guide text is classical electrodynamics, Jackson. I find that book is higher my current level. I have the math tools, but what book do you recommend to use before the Jackson.
15. ### Lagrangian and Slonczewski-like torque

To include slonczewski-like torque in the Lagrangian there enter as dissipation by Rayleig function? ST= σ m x (m x mp) where m is the magnetization in free layer and mp current direction in the pinned layer (-z). The Rayleig function is: RF=(dm/dt+σ m x mp)2 Then L= ∫ (RF+E)dx Thanks
16. ### Classical Book to learn classical electrodynamics

Hi, What book could you recommend for a first course in classical electrodynamics? Thank you
17. ### Make disk in oommf

Hi, I'm just starting to use oommf. I wish to see the evolution of the magnetization of a dot, which has uniaxial anisotropy. Command lines I use are #Geometry proc Disco {x y z} { global Diametro Ms set rx [expr {2*$x-1}] set ry [expr {2*$y-1}] if...