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

In summary, the conversation discusses a question about relativistic kinematics involving a source and detector on a rotating disk. The question asks for the frequency of radiation detected by the source at a certain angle. The participants discuss possible approaches and one suggests referencing a book for the solution.
  • #1
eep
227
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 [itex]\phi[/itex] apart on the edge of a rotating disk. The source emits radiation at frequency [itex]\omega[/itex] 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?
 
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  • #2
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.
 
  • #3
Thanks - picked the book up today, that thing weighs a ton!
 

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

What is a rotating frame of reference?

A rotating frame of reference is a coordinate system that is rotating relative to an inertial frame of reference (a non-accelerating frame of reference). It is used to describe the motion of objects in situations where the reference frame itself is rotating, such as a rotating merry-go-round or a spinning top.

How does a rotating frame of reference affect the laws of physics?

In a rotating frame of reference, the laws of physics still hold true, but they may appear to be different due to the effect of Coriolis and centrifugal forces. These forces arise due to the rotation of the frame and can cause apparent deviations from the expected motion of objects.

Why is it important to use a rotating frame of reference?

A rotating frame of reference is important in situations where the reference frame itself is accelerating or rotating, as it allows us to accurately describe the motion of objects in these situations. It is also used in many areas of physics, such as fluid dynamics and celestial mechanics, to simplify calculations and make them more accurate.

How does the Coriolis effect work in a rotating frame of reference?

The Coriolis effect is an apparent force that appears in a rotating frame of reference, causing objects to deviate from a straight path. This effect is due to the rotation of the frame and the fact that different points on a rotating object have different velocities.

Can a rotating frame of reference make objects appear to violate the laws of physics?

No, a rotating frame of reference does not actually violate the laws of physics. It simply appears to do so due to the effects of Coriolis and centrifugal forces. These forces are a result of the reference frame itself, not the objects within it, and can be accounted for in calculations to accurately describe the motion of objects.

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