Hi!
There is a concept I don't understand and would love to have is cleared...
What is the meaning of a lattice with a basis?
What do I need it for?
Say I have a honeycomb structure. (fig 1) and a basis as mentioned there (did I understand it right? is it the basis? )
why does it become...
Hi there! I'm having trouble understanding the transistor circuit analysis. Hope you could help me :)
First I need to find the active region of the transistor. What I saw in the solutions was an assumption that the transistor is in saturation region and then:
VBB=IbRb+Vbe+IeRe...
Hi!
I hope this is the right forum... I am having trouble with Mathematica:
Maybe someone could help out of his experience ?
I created w[x]:=RandomReal[NormalDistribution[0,1],x]
I got it's plot.
Now I want to integrate it: I wish to receive another graph, which is the plot of the...
Hi! I can't understand something in field theory and need your assistance:
I wish to understand why a particle of mass m^2<0 can't exist.
For a massive particle, in its reference frame, one would write:
p_\mu=(m,0,0,0). I understand that.
But for m=0, why is:
p_\mu=(p,0,0,p)
And for m^2<0...
Hi guys!
There is something I would like to get your help with...
I am looking at the equation:
W^{\mu}=-\frac{1}{2} \varepsilon^{\mu\nu\lambda\sigma}M_{\nu\lambda}p_{\sigma}
Which is, if I understand correctly,a Casimir Operator.
Now, I wish to look at a particle in its rest reference...
Hi you guys!
I am having a hard time understanding some stuff in this context.
I was not able to find any guidance in books or anything.
say I want to calculate:
[W^2,p^\alpha]=0, W=\frac{m}{2}\varepsilon^{\mu\nu\lambda\varepsilon}M_{\mu\lambda}p_\delta
How do I do that? I can't...
Hello!
I have a question regarding a method I saw every now and then:
Say I have a system containing of two masses, attached to one another by a spring. Each is attached to a wall by another spring.
Now I wish to know the eigen vectors and eigen values( \omega) of movement.
I get:
\ddot...
Hello! I am having trouble understanding the whole primitive function thing in complex analysis.
How do I check if a certain function, say [itex] \frac {sin(z)} {z} [/tex]
has a primitive, say in C/{0} ?
What is the intuition? My intuition is that 0 is the only singularity, so if it is...
Hello! I ask this question in this forum because I wish to be given a general explanation.
Hope it is OK
given this metric:
ds^2= \frac {dt^2} {t^2}- \frac{dx^2} {t^2}
I wish to calculate the geodesics.
S=\int{ \frac {d} {d\lambda} \sqrt{\frac {1} {t^2} \frac {dt^2} {d\lambda^2}-...
Finding Geodesics
What I wish to understand, is how to solve this one:
given this metric:
ds^2= \frac {dt^2} {t^2}- \frac{dx^2} {t^2}
I have to calculate the geodesics.
S=\int{ \frac {d} {d\lambda} \sqrt{\frac {1} {t^2} \frac {dt^2} {d\lambda^2}- \frac{1} {t^2} \frac {dx^2}...
Hello!
I need to find the relation between E^{2}-B^{2} and F_{\mu\nu} F^{\mu\nu}
Actually, I need to use this relation to determine that the first is a scalar.
What I can't understand is how these notations match the formal definition:
If I multiply a matrix by another (same size) I should...
Hello! I fail to understand this question... I don't even know how to approach it...
Given: m\frac{d^{2}x^{\mu}} {d\tau^{2}} =e{F^{\mu}_{nu}} \frac{dx^{\nu}} {d\tau}
I have to define u^{\mu}= \frac {dx^{\mu}} {d\tau^2}
and obtain:
u^0= cosh(\frac {eE\tau} {m}) u^0(0)+ sinh(\frac {eE\tau}...
Hello again. Thank you guys. You have been great help...
I have another one:
Given a potential well- 2a is it's width, and in the middle - there is a delta potential:
V(x)= \frac {\hbar^2} {2m} \frac {\lambda} {a} \delta(x)
I am looking for the odd solution to this problem.
I thought...
Hello!
My exam is tomorrow... Help will be much appreciated...
Say l=0 is given. My hemiltonian is \bar {H}=\frac {1} {\hbar} \Omega (\vec {n} \cdot \vec {L})^2
And we use "base states" that are L_z eigenstates, |1 m>
n is a general direction unit vector.
Now, I am looking for...
Hello again!
Say I have a potential well, between 0 and a. I also know how the wave function looks like for (t=0):
\psi(x,0)= \frac {2bx} {a} for 0<x<\frac {a} {2}
and
\psi(x,0)= 2b(1- \frac {x} {a} ) for \frac {a} {2} <x<a
Now, I wish to find the wave function of a general time...
Hello!
There is something I can't understand...
\psi(0)= \frac {1}{\sqrt 5}|1>+ \frac {2i}{\sqrt 5}|2>
I need to find <H> for \rightarrow \psi(t)
For
E_n= \hbar \omega (n + \frac {1}{2}) , \hat {H} =(a^\dagger a+1/2)
These make me understand that this problem is one dimensional. (+1/2 in...
Hello again!
Facing some problems (my exam is taking place tomorrow... help is needed. Many thanks in advance!)
I need to find an approximation for a retarded time. I don't understand how. This is what my lecturer wrote:
sin(\varphi-\omega t)=exp(i\varphi'-i\omega(t-r/c)-i\omega(r'cos\theta...
Hello ! I have an exam this Wednesday... your help will be appreciated...
There are two types of questions I can't figure out how to answer...
the first is this one:
Find the potential between two parallel planes. The first is in x=0, the second in x=L.
\Phi(x=L)=\Phi_0 |sin(ky)|
and...
Hello! I am new here...
I am a physics student, seeking for help. There is something I just can't seem to understand...
Your help will be much appreciated...
In my exercise, I have the following Hamiltonian:
H=\frac{p_x^2}{2m}+\frac{p_y^2}{2m}+\frac{1}{2}m \omega^2 (x^2+y^2)+\lambda xy
I was...