I was looking for information on how the photo electrons are emitted when under X-ray radiation. In this ancient review paper here http://journals.aps.org/pr/pdf/10.1103/PhysRev.30.488 [Broken] they state that the most common angles for non polarized X-ray beams (of various energies) range...
The title was too long, original question was: Why is the relative biological effectiveness (RBE) of photon and electron the same ? I was suspecting the charge of electron to possibly have some effect...
Also, in biological matter, would there be a difference between photon damage and...
Hi all,
I've been seeing this again and again, that delayed neutrons are the ones that are allowing thermal nuclear reactors to work etc. etc.
What I do not understand is how are prompt neutrons controlled and how delayed ones are allowed to "do their thing" no problem ? Wiki says...
Hi,
I am revising my intro to nuclear physics class and was wondering why is parity so important ?
I mean OK, I get it, physicists are crazy about symmetries, but I do not understand what does it physically mean...
I was wondering if someone could possibly talk me through its importance and...
Homework Statement
For whoever does not want to read the attached problem:
Firstly, I need to express the arc-length from given x=r\cos\theta, y=r\sin\theta z = f(r), \text{ where } f(r) \text{ is an infinitely differentiable function and } r=r(\theta) \text{ i.e. parameter is } \theta I...
Hi all!
I just wanted to ask if anyone is finding the usage of method of characteristics difficult ? I sort of feel, that it is a very simple approach to solving PDE's, but I get easily lost, when for instance, we have to keep switching back and forth between variables and such. When it comes...
Hi all!
Another questions which is due to the gaps in my calculus knowledge.
In these notes: http://people.hofstra.edu/Gregory_C_Levine/qft.pdf in the line above eq. (1) where it says that notation P is now unecessary, is it because \partial{ (p+\delta p)} is much smaller than p+\delta p...
I have looked up a few derivations of Noether's Theorem and it seems that chain rule is applied (to get a total derivative w.r.t. q_{s} ( = q + s ) is often used. What I do not understand is why this is legitimate ? If we start with L=L(q,q^{.},t) how can we change to L=L(q_{s}...
Homework Statement
Show that
(\Delta A)^{2} = \langle \psi |A^{2}| \psi \rangle - \langle \psi |A| \psi \rangle ^{2}\\
\phantom{(\Delta A)^{2} }=\langle \psi | (A - \langle A \rangle )^{2} | \psi \rangle ,
where \Delta A is the uncertainty of an operator A and \langle A \rangle is the...
Homework Statement
Find the geodesics on a sphere g(x,y,z)=x^{2}+y^{2}+z^{2}-1=0
arclength element ds=\sqrt{dx^{2}+dy^{2}+dz^{2}}
Homework Equations
f(x,y,z)=\sqrt{x'^{2}+y'^{2}+z'^{2}} where x'^{2} \text{means} \frac{dx^{2}}{ds^{2}} and not d^{2}x/ds^{2}
The Attempt at a...
Homework Statement
Find the geodesics on a cone of infinite height, x^{2}+y^{2} = \tan{\alpha}^{2}z^{2} using polar coordinates (x,y,z)=(r\cos{\psi},r\sin{\psi},z) with z=r\tan(\alpha)
The Attempt at a Solution
I am not sure with how should I expres the element dz^{2} ? When it is a...
Not really a homework question, just the notes are confusing me.
Homework Statement
Let S be a functional.
(Given without proof)
If S is differentiable its derivative \delta S is uniquely defined as
\delta S = \int_{x_{0}}^{x_{1}}\frac{\delta S}{\delta \gamma} \delta \gamma dx where...
Hi all,
I expect that this might be rarely taught (as I have not found much on the web).
But maybe some of you have encountered this. I attach the problem
At the end the author says to take the limit as t goes to 1. But to me, it does not make sense to look at something that is ε<x<=ε...
Homework Statement
Sketch the solution to the IVP
u_{t}+uu_{x}=0 \\ u(x,0) = e^{-x^{2}}
Homework Equations
Monge's equations \frac{dt}{d\tau} = 1 \\ \frac{dx}{d\tau}=u \\ \frac{du}{d\tau}=0
The Attempt at a Solution
I think I do not really need the Monge's equation, but I have no...
Homework Statement
A diffraction grating is ruled with 500 lines/mm and
is 1 mm in width. Calculate the angular width of
the intensity peaks to the first minimum in the
Fraunhofer diffraction pattern of this grating, when
illuminated with light of λ = 600 nm.
Homework Equations
n-...
Homework Statement
Show that
\frac{d}{dt}\int \rho r^{2}\phi dr = \int \rho r^{2}\frac{d\phi}{dr} dr
Homework Equations
Fundamental theorem of calculus
The Attempt at a Solution
So I follow the derivation from the textbook and I think I get the rather sneaky rearrangement of...
Homework Statement
I do not understand how the vector (1 -1 0)T represents the axis tangent to the disk at Q.
The Attempt at a Solution
Tried thinking in terms of simple vector addition, but just got another vector in the radial direction...
I mean, (1 -1 0)T is parallel to a tangent...
This is not really a homework problem, I do not understand the concepts. The attachment below is as informative as the slides provided are. The course seems to be based on H.J. Pain's book "waves and vibrations".
I know that the information provided is limited, but there is little I can...
This is not really a homework questions, rather a concept based one. I am studying from Fraleigh's ''Intro to abstract algebra'' and in chapter 15 it states, that for a group G and normal non-trivial subgroup of N of G, the factor group G/N will be smaller than G. I am not sure how he counts the...
Homework Statement
Clasify the group Z4xZ2/{0}xZ2 using the fundamental theorem of finitely generated abelian groups.
Homework Equations
FTOFGAG: In short it states that every finitely generated abelian group G is isomorphic to a direct product of cyclic groups of the form...
Homework Statement
Let \alpha:G \rightarrow H be a homomorphism and let x\inG
Prove \alpha(<x>) =<\alpha(x)>
Homework Equations
α(<x>) = α({x^{r}: r ∈ Z}) = {α(x^{r}) : r ∈ Z} = {α(x)^{r}: r ∈ Z} = <α(x)>.
I do not understand how can we take out the 'r' out of a(x^{r}) to...
Homework Statement
Two left cosets aH, bH of H in G are equal if and only
if a^{−1}b ∈ H. This is also equivalent to the statement b ∈ aH.
Proof:
Suppose that aH = bH. Then e ∈ H. So, b = be ∈ bH. If
aH = bH then b ∈ aH. So, b = ah for some h ∈ H. But, solving for
h, we get h = a
−1
b...
This is not a specific HW/CW question, just a gap I have and want to fill.
I came from a school in which calculus was only introduced in the last year so I learnt only the basics.
Now, I see more and more stuff like taking an expression, say A=B+C and simply making it to a dA=dB+dC. The...
[SOLVED] Superposition of two wavefunctions
Homework Statement
The problem is more of complex number arithmetic more then conceptual :
Homework Equations
|\psi|^{2}=\psi\psi^{*}
The Attempt at a Solution
I simply used the equation given above, but instead of getting 2Re{...} I...
Homework Statement
Problem is described in the picture
I do not understand how can \alpha^{'}R=a^{'}.
The dimensions do not seem correct. Angular velocity x distance from the origin = tangential velocity, is that correct ? How can this equal acceleration then ?
3. Attempt to solution
I...
Homework Statement
Let H be a subgroup of group G. Then
H \unlhd G \Leftrightarrow xHx^{-1}=H \forall x\in G
\Leftrightarrow xH=Hx \forall x\in G
\Leftrightarrow xHx^{-1}=Hxx^{-1} \forall x\in G
\Leftrightarrow xHx^{-1}=HxHx^{-1}=H \forall x\in G...
Hello all,
Firstly, sorry for the long post, I was just wondering if someone is in a similar position and would like to hear their thoughts and how they deal with certain things. If it is too long, just skip to the questions I have under each paragraph.
I was never spending much time...
Homework Statement
A comet is approaching the Sun from a vast distance with velocity V. If the Sun exerted no force on the comet it would continue with uniform velocity V and its distance of closest approach to the Sun would be p. Find the path of the comet and the angle through which it is...
Homework Statement
I decided to revise my mechanics course and came across a problem involving a system with three springs (say, different k's) and two masses (say different).
The s1-m1-s2-m2-s3 system has the outer springs connected to walls of infinite mass.
I was interested in what...
Hello all,
I am wondering if I could get some advice from people who have done MHD/Plasma Physics (or even better, went to do something like 'MSc in Fusion Energy' which is offered by York University). Ideally I would like to work somewhere with fusion energy (although it is vastly dominated...