Question
Synchrotron radiation is emitted mostly along the direction of motion due to this effect. For 10 points each:
[10h] Name this effect that causes isotropic radiation in a decaying particle’s rest frame to be concentrated in a cone in the lab frame.
ANSWER: relativistic beaming [or the headlamp effect; or the headlight effect; or the searchlight effect; accept Doppler beaming]
[10m] For a photon emitted perpendicular to the motion in the rest frame, the cosine of the emitted angle will equal this expression in the lab frame. The square root of “one minus this expression squared” is the denominator of the Lorentz factor.
ANSWER: v over c [or relativistic beta; or v divided by c; accept u over c; accept answers indicating the ratio of the particle’s velocity to the speed of light; prompt on v or u]
[10e] Along with changing angles, the frequency of radiation is also changed when moving from rest to lab frames due to this effect. This effect causes sound from an approaching car to sound higher pitched.
ANSWER: Doppler effect
<Physics>
Summary
| 2024 ACF Regionals @ Berkeley | 01/27/2024 | Y | 3 | 16.67 | 100% | 67% | 0% |
| 2024 ACF Regionals @ JMU | 01/27/2024 | Y | 1 | 20.00 | 0% | 100% | 100% |
| 2024 ACF Regionals @ Ohio State | 01/27/2024 | Y | 1 | 20.00 | 100% | 100% | 0% |
| 2024 ACF Regionals @ Rutgers | 01/27/2024 | Y | 1 | 30.00 | 100% | 100% | 100% |
| 2024 ACF Regionals @ Vanderbilt | 01/27/2024 | Y | 1 | 10.00 | 100% | 0% | 0% |
Data
| UNC B (UG) | Maryland A (Grad) | 10 | 10 | 0 | 20 |