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1d
comment Motion question
What are you confused about?
1d
comment What will be final velocity of three charges $q$, $q$, $2q$?
@ophelia, your first point is a typo, which I have fixed. Your second point is valid. I believe what I need to show is that $\theta$ actually converges at infinity.
1d
comment What will be final velocity of three charges $q$, $q$, $2q$?
@PeterShor, I have a written a solution below that seems right, but there's something I can't prove. Is there a way to show that the shape of the triangle actually converges at infinity?
1d
comment What will be final velocity of three charges $q$, $q$, $2q$?
@AnubhavGoel, $\theta$ is $\pi/6$ at $t=0$. When $B$ moves, $\theta$ changes.
1d
comment What will be final velocity of three charges $q$, $q$, $2q$?
@Fire, I have updated my solution, but it isn't particularly neat. Do let me know if you find something simpler.
1d
comment What will be final velocity of three charges $q$, $q$, $2q$?
@ophelia, I have included more details in my answer. Note that the numerical result has been corrected. Let me know if you still think something is incorrect.
2d
comment What will be final velocity of three charges $q$, $q$, $2q$?
@AnubhavGoel, when $B$ is in the equilateral triangle, the force is not along $OB$, because of the unequal charges. This causes $\theta$ to change, until $t\rightarrow\infty$ when the force is along $OB$.
Feb
9
comment What will be final velocity of three charges $q$, $q$, $2q$?
@AnubhavGoel, if the force is not along $OB$ at $t\rightarrow\infty$, the angle $\theta$ would not be a constant.
Feb
3
comment What will be final velocity of three charges $q$, $q$, $2q$?
@AnubhavGoel, if the force is not along $OB$, the angle $\theta$ would change.
Jan
28
comment Electron self-energy calculation for a $k$-dependent interaction
You might want to check out the similar calculation for electron-phonon interaction, for example in the book by Mahan.
Jan
26
comment Charge inside a charged spherical shell
It is certainly unintuitive. However, let's say the charge $Q$ is somewhere on the left of the shell's center. Let $A$ be the part of the shell on the left of $Q$, and $B$ be those on the right. $A$ pushes $Q$ to the right, while $B$ pushes $Q$ to the left. The force by $A$ is intuitively stronger since it is nearer to $Q$. However, $B$ has more charges, and the two effects somehow cancel out exactly.
Jan
26
comment Open-source code for computing response functions
@CuriousOne, thanks, the hepforge projects look invaluable. It would be great if something similar exists for the condensed matter community too.
Oct
22
comment Why is there a superconducting dome in superconductors?
You may be interested in this paper: Sci. Rep. 2, 381 (2012).
Oct
22
comment Why is there a superconducting dome in superconductors?
Doping does not necessarily increase the density of states at the Fermi surface. Regardless, I believe the origin of the dome is still an open problem. One way to look at it is that doping changes the Fermi surface. This then affects the interactions between electrons and spin fluctuations that are responsible for superconductivity. When the system is overdoped, the interactions become weaker and $T_c$ decreases.
Aug
31
comment Can hydrogen be used for superconductors?
Superconducting transition temperatures depend on many things in addition to the mass of the isotopes.
Aug
29
comment What is a Fermi arc?
The Fermi surface of a 2D system is typically a closed contour that encloses a region in momentum space. However, in some cases, the contour is not closed. Such a Fermi surface is known as a Fermi arc. See DOI:10.1126/science.1248783 for some experimental results about Fermi arcs in the cuprates.
May
4
comment Two solutions, A+ and A-, for masses connected via springs
Basically, we want to find $A_j$ as a function of $j$. It turns out that both $A_j=A_+ e^{i\theta j}$ and $A_j=A_- e^{-i\theta j}$ work, for some $A_+$, $A_-$, and $\theta$ independent of $j$. You should be able to find $\theta$ in terms of $\omega$ and $\omega_0$.
May
3
comment Graph of energy stored in capacitor?
Let us continue this discussion in chat.
May
3
comment Graph of energy stored in capacitor?
Try starting with $Q=Q_0-It$, where $Q_0$ is the initial charge the capacitor has.
May
3
comment Graph of energy stored in capacitor?
Alternatively, you can write up your own answer, and show us how you can get correct graph.