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#A2 PHYSICS > 2- Chapter 17 - Matter > Flashcards

2- Chapter 17 - Matter Flashcards

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1
Q

What is a positron?

A

Antimatter/Antiparticle fr an electron with the same mass but opposite charge.

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2
Q

What happens when an antimatter meets its mirroring matter?

A

They both annihilate and release 2 gamma rays witch total energy mc2

The two gamma rays have equal energy and travel opposite directions

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3
Q

What is the direction in a feynman diagram?

A

Bottom to top

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4
Q

Whats the symbol for a photon in a feynman diagram?

A

A wavey live with a arrow at the end.

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5
Q

Symbol for a gluon on a feynman diagram

A

a spring with an arrow at the end.

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6
Q

What are fermions?

A
  • Eg electrons
  • Only one per energy state
  • HAve quantised amounts of spin
  • Phases add up with opposite phase so if two identical met youd have 0 amplitude
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7
Q

What are bosons?

A
  • eg photons
  • like to be in the same state
  • Phases add when together
  • Are exchanged in interactions
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8
Q

How can matter be created

A

A gamma ray with energy > 2mc2 passes by a neuclus and releases a positrona nd electron

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9
Q

What is a neutrino?

A

Small, massless , Chargeless - no interaction with matter

They account for uneven beta decay

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10
Q

How does uneven beta decay happen

A

a neutrino of random energy is released and is invisible.

THis means the electron wil have a random energy and random path length

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11
Q

What are baryons?

A

Heavy particles eg proton and neuton

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12
Q

What are leptons?

A

light particles eg electron , (electron) neutrino

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13
Q

Equation for the beta decay of Strontium

A
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14
Q

What is the weak interaction?

A

the exchange of the bosons Z0 (neural) , W+ and W-

A neutron can change into a protom by emmiting a W- boson (which decays into an electron and anti neutrino)

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15
Q

What does alpha scattering in gold show?

A

SHows that a charged neuclues must exist, and that its positive.

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16
Q

WHat is the charge of an Up quark?

A

+2/3e

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17
Q

What is the charge of a down quark?

A

-1/3e

18
Q

What is a proton made of?

A

uud

19
Q

What is a neutron made of?

A

udd

20
Q

Quark combination rules?

A
  • must combine to be colourless
  • This can happen in trios to create a baryon
  • Or in pair to create a meson
21
Q

What is a gluon?

A

Holds quarks together thought energy/colour exchange

22
Q

How the the force of a gluon change

A

it increases as you pull the quarks further apart

23
Q

what does a red/blue gluon do?

A

swaps a red and a blue quarks colour around

24
Q

whats different about an antimatter?

A

has opposite charge,lepton and baryon number , colour

25
Q

what causes electromagnetic interactions?

A

the exchange of photons

26
Q

En is proportional to

A

-1/n2

27
Q

what is a continuous spectrum?

A
  • From incandescent light
  • all colours with no gaps
  • the hotter the body the more blue/violet the predominant colour is.
28
Q

What is line emmision spectra?

A

typical of exited gasses

  • only certain wavelegth are present
  • different pattern for each element which appear as bright lines
29
Q

What does the (atomic) hydrogen emmision spectr look like?

A
30
Q

En For hydrogen =

A

-13.6eV x 1/n2

31
Q

What explains the emmision spectra of hydrogen?

A

The first seris is from an electron terminating at level 1 whcih means that energy difference is higher and this explains the bunching of lines in the emission spectra.

32
Q

What is a line absorbtion spectra?

A

What frequencies are absorbed by a object.

Its the same as the objects emmision spectra but with dark spons where the light spots freviously were.

(used in redshift)

33
Q

Why is it -1/n2 in the emmision spectra?

A

as the charges are negative and get attracted to the positive neaclus

34
Q

What is Eionise

A

0

35
Q

Whats different about electron scattering?

A

very few go through large scattering angles and most pass stragight thoguh

36
Q

How are volume and mass number related?

A

r=r0A1/3

Volume is proportional to mass number

37
Q

What happens when you poull two quarks further apart

A

the force holding them together by the gluon gets stronger and stogner until new matter is created usually as a meson.

38
Q

de broglie wavelength=

A

h/p

39
Q

quantum jumps in energy level

A

E=hf=Einitial-EFinal

40
Q

three generations of fundamental particles?

A
  1. Electron, electron-neutrino Down,Up
  2. Muon, Muon-neutrino stange,charmed
  3. Tau,Tau-neutrino bottom,top

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