2- Chapter 17 - Matter

Question 1

What is a positron?

Answer 1

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

Question 2

What happens when an antimatter meets its mirroring matter?

Answer 2

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

The two gamma rays have equal energy and travel opposite directions

Question 3

What is the direction in a feynman diagram?

Answer 3

Bottom to top

Question 4

Whats the symbol for a photon in a feynman diagram?

Answer 4

A wavey live with a arrow at the end.

Question 5

Symbol for a gluon on a feynman diagram

Answer 5

a spring with an arrow at the end.

Question 6

What are fermions?

Answer 6

• 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

Question 7

What are bosons?

Answer 7

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

Question 8

How can matter be created

Answer 8

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

Question 9

What is a neutrino?

Answer 9

Small, massless , Chargeless - no interaction with matter

They account for uneven beta decay

Question 10

How does uneven beta decay happen

Answer 10

a neutrino of random energy is released and is invisible.

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

Question 11

What are baryons?

Answer 11

Heavy particles eg proton and neuton

Question 12

What are leptons?

Answer 12

light particles eg electron , (electron) neutrino

Question 13

Equation for the beta decay of Strontium

Answer 13

Question 14

What is the weak interaction?

Answer 14

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)

Question 15

What does alpha scattering in gold show?

Answer 15

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

Question 16

WHat is the charge of an Up quark?

Answer 16

+2/3e

Question 17

What is the charge of a down quark?

Answer 17

-1/3e

Question 18

What is a proton made of?

Answer 18

uud

Question 19

What is a neutron made of?

Answer 19

udd

Question 20

Quark combination rules?

Answer 20

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

Question 21

What is a gluon?

Answer 21

Holds quarks together thought energy/colour exchange

Question 22

How the the force of a gluon change

Answer 22

it increases as you pull the quarks further apart

Question 23

what does a red/blue gluon do?

Answer 23

swaps a red and a blue quarks colour around

Question 24

whats different about an antimatter?

Answer 24

has opposite charge,lepton and baryon number , colour

Question 25

what causes electromagnetic interactions?

Answer 25

the exchange of photons

Question 26

E_n is proportional to

Answer 26

-1/n²

Question 27

what is a continuous spectrum?

Answer 27

* From incandescent light * all colours with no gaps * the hotter the body the more blue/violet the predominant colour is.

Question 28

What is line emmision spectra?

Answer 28

typical of exited gasses * only certain wavelegth are present * different pattern for each element which appear as bright lines

Question 29

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

Answer 29

Question 30

E_n For hydrogen =

Answer 30

-13.6eV x 1/n²

Question 31

What explains the emmision spectra of hydrogen?

Answer 31

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.

Question 32

What is a line absorbtion spectra?

Answer 32

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)

Question 33

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

Answer 33

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

Question 34

What is E_ionise

Answer 34

0

Question 35

Whats different about electron scattering?

Answer 35

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

Question 36

How are volume and mass number related?

Answer 36

r=r₀A^1/3 Volume is proportional to mass number

Question 37

What happens when you poull two quarks further apart

Answer 37

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

Question 38

de broglie wavelength=

Answer 38

h/p

Question 39

quantum jumps in energy level

Answer 39

E=hf=E_initial-E_Final

Question 40

three generations of fundamental particles?

Answer 40

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