kmjhw Flashcards
Recall the historical measurement(s) of the speed of light
Historical measurements of the speed of light:
- Roemer’s Measurement of Io’s orbit
- Fizeau’s Cogwheel
- Foucault’s Mirrors
Describe how Roemer measured the speed of light
Roemer observed the orbital period of Io was inconsistent due to the speed of light being finite and Earth’s relative velocity to Io’s orbit.
Receding velocity –> larger apparent period
Approaching velocity –> smaller apparent period
Time discrepancy = 22 minutes to cross the length of Earth’s orbit
Describe how Fizeau measured the speed of light
Fizeau passed a beam of light through a toothed cogwheel with slits and reflected back via a mirror. Based on the angular velocity of the cogwheel and the velocity of the speed of light, the speed may or may not pass back through a slit or get blocked.
Recall the contemporary measurement(s) of the speed of light
Essen Cavity Resonator
Last-Ditch: Rosa & Dorsey [Used Maxwell’s findings to calculate the speed of light, accuracy was inhibited by the definition of the standard unit of Ohms]
Describe how Essen measured the speed of light
Essen used a Microwave Cavity Resonator with microwaves of a known frequency. The resonator was of a variable length –> Essen found the exact lengths for which resonance occurred, which allowed him to find the wavelengths.
Explain how Planck accounted for the shape of the blackbody curve
Planck proposed that the absorption and emission of radiation are inherently quantised as discrete amounts, known as quanta.
At higher frequencies, a greater gap exists between energy levels and thus, there is a lesser likelihood that atomic oscillators exist in an excited state. Ultimately, a lower intensity at low wavelengths.
Recall the experimental evidence for Special Relativity
Rossi-Hall –> muons
Experiment conducted on Mount Washington
A greater quantity of mu-mesons was detected on the surface of the Earth than predicted by its half-life.
Length contraction [mu-meson] + Time dilation [stationary observer]
Hafele-Keating experiment
Atomic clocks flown to the East and West; Earth rotation eastly
Features of Stars
- Cepheid Variables – Period-Luminosity relationship
- Cosmic Microwave Background Radiation
Hydrogen fussion
- Proton-proton chain
- CNO cycle
- Triple alpha
Features of Nuclear Stations
Moderators - Heavy water; slow down neutrons more effective
- Control Rods - Boron or Cardium absorb neutrons
- Coolant – as energy source
- Radiation shield
Particle Detectors
Cloud chamber – gas – Anderon discovered the positron
Bubble Chamber – liquid
Pauli’s neutrino
Electrostatic accelerators – cathode gun etc
Linear accelerators – radio frequency alternating voltage; cylinder electrodes increasing in length
Cyclotron – 2 conductive dees - separation for tangential acceleration by electric field reverses every half period; magnetic field centripetal force
Synchrotron – Evacuated pipes next to magnets; magnetic field and frequency of bursts of electric field increases
Standard Model of Matter
Fundamental particles: Leptons, quarks, and gauge bosons
Quarks - Up (2/3) and Down (-1/3)
Leptons - Electon, muon, tau and the corresponding neutrinos
Gauge Bosons - Graviton, Photon, Gluon, Z/W-Boson
Hadrons: Mesons (2) and Baryon (3) quarks
Higgs-Boson – mass
