What is the detected frequency of radiation in a rotating frame of reference?

eep
Messages
225
Reaction score
0
Hi,
I've run into a relativistic kinematics question that I'm not sure how to approach. The question states:

"A source and a detector are spaced a certain angle \phi apart on the edge of a rotating disk. The source emits radiation at frequency \omega in it's instantaneous rest frame. What frequency is the radiation detected at? Hint: Little information is given because little is needed."

I have no idea how to approach this. Since the detector and source are on a rotating disk, they are not connected by inertial frames. I want to say that their instantaneous rest frames are somhow connected, that is, the relative velocities of the frames are always the same. But where do I even begin? I thought perhaps I could work out where the detector would receive a photon emmited by the source, and maybe do a lorentz boost from the instantaneous rest frame of the source to a frame where both detector appear to be moving on the edge of the disk, then do a boost from that frame to the frame of the detector using the velocity of the detector at the time it would be received, but that seems complicated... what am I missing here?
 
Physics news on Phys.org
Can you get hold of the book Gravitation by Misner, Thorne, and Wheeler? The solution to this problem is given in section 2.8 The Centrifuge and the Photon.
 
Thanks - picked the book up today, that thing weighs a ton!
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top