OCR Advancing Physics: Probing Deep into Matter

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  • Created by: Caraa
  • Created on: 04-06-13 19:02
In the goil foil experiment, what did the fact that some alpha particles were scattered at angles greater than 90 mean?
They are striking something more massive than themselves
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In the goil foil experiment, what did the fact that most alpha particles went straight through mean?
Atoms are mostly empty space
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In the goil foil experiment, what did the fact that some alpha particles were deflected at significant angles mean?
The center of the atom must be tiny but contain a lot of mass
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In the goil foil experiment, what did the fact that the alpha particles were repelled mean?
The nucleus must have a positive charge and hence since atoms are neutral overall the electrons must be on the outside
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What is the equation for closest approach?
r = kQq / kinetic energy
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When a particle is at its closest approach, what is its electric potential energy equal to?
Inital kinetic energy
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What is special about hadrons?
They feel the strong attraction and are made of quarks
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Protons are the only stable baryon, what do the others decay to?
A proton
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What is special about leptons?
They dont feel the strong attraction only the weak
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Electrons dont decay but what do muons and taus decay to?
A electron
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What is the mass and charge of a neutrino?
Zero and zero
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What is the difference between a particle and its antiparticle?
Opposite charge and baryon/lepton number
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When energy is converted to mass what do you need to make equal amounts of?
Matter and antimatter
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What are annihilation and pair-production?
Annihilation is where two particles (matter and anti) convert into energy and pair production is the opposite
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What is the charge of a up quark?
+2/3
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What is the charge of a down quark?
-1/3
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What is the baryon number of any quark?
+1/3
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What is the combination of quarks for a proton?
uud
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What is the combination of quarks for a neutron?
udd
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Why is there no such thing as a free quark?
The energy you would use to try to separate the quarks would actually get changing into a quark antiquark pair
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Bosons are exchanged to show forces. What are the bosons and what are they used for?
Gluon for strong, photon for electromagnetic, weak for W+,W-, gravition for gravity
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How does a linear accelerator work?
Alternating charge applied to electrodes and timed so that particles are always attracted to the next electrode.
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How does a cyclotron work?
Uses two semicircular electrodes to accelerate charged particles across a gap. an alternating pd is applied so the particles are attracted from one side to the other. A magnetic field is applied to keep them moving in a spiral.
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How does a synchrotron work?
Electromagnetic keep particles moving in a circular motionz
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How do electrons move up and down energy levels?
Emitting and absorbing photons
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What does this mean about the energy levels?
They can only take certain values
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What is the pauli exclusion principle that fermions obey?
No two fermions can exist in the same quantum state at the same time. So no more than two electrons can be in the same energy level
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Card 2

Front

In the goil foil experiment, what did the fact that most alpha particles went straight through mean?

Back

Atoms are mostly empty space

Card 3

Front

In the goil foil experiment, what did the fact that some alpha particles were deflected at significant angles mean?

Back

Preview of the front of card 3

Card 4

Front

In the goil foil experiment, what did the fact that the alpha particles were repelled mean?

Back

Preview of the front of card 4

Card 5

Front

What is the equation for closest approach?

Back

Preview of the front of card 5
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