Evidence for relativistic mass + Particle Accelerators Flashcards
What did the experiment provide evidence for
Bertozzi’s experiment provided evidence for the variation of kinetic energy with speed giving confirmation of relativistic mass - as speed increases so does mass
What evidence was provided from the experiment
As electrons moved closer to the speed of light, their speciifc charges decreased compared to the value hen at rest therefore their mass changed (as charge is constant)
What was Bertozzi’s experiment (4)
1) Bertozzi used linear particle accelerators to accelerate pulses of electrons to a range of energies - 0.5MeV to 15MeV
2) The time taken to reach the aluminium disc was measured for each electron of each energy so that their speeds could be calculated
3) He used the heat generated by the collisions at each energy to calculate the kinetic energy of the particles immediately after impact because Ek = heat generated
4) He then plotted a graph of v^2/c^2 (y) against Ek/m0c^2 (x) and then showed a comparison against Einstein’s special relativity and Newton’s classical mechanics
What did Bertozzi’s results show
As the energy of the electrons increased, the speed of the electrons did not increase as you would expect from 0.5mv^2 but instead tailed off towards a maximum value of c
What did the graph look like
Newtons was almost a vertical line next to the y axis
Einsteins was the usual curve just on different axes i.e. r shaped with a horizontal asymptope at y=1
Bertozzi’s was extremely similar, points connected by straight lines
What did the graph show
Bertozzi’s results closely matched those as predicted by Einstein. His graph was very similar to that which Einstein’s theories predicted giving direct evidence of its validity.
Consider a charged particle being accelerated at high speeds close to the speed of light in free space inside a particle accelerator:
Kinetic energy transferred to a particle Q being accelerated from rest through a pd of V =
Ek = Work done = QV
Consider a charged particle being accelerated at high speeds close to the speed of light in free space inside a particle accelerator:
Total energy =
E = mc^2 = Ek + E0 = Ek + m0c^2 = QV + m0c^2
What type of experiment was it
An electron-beam experiment
What did Bertozzi’s results show
His results show that as you accelerate a charged particle through higher voltages (i.e. increase its energy) then its speed increases to a limiting value of c and its mass increases (as kinetic energy still increased once v was close to c)
