1.7 Particles - Particle Interactions

Question 1

The four interactions:

Answer 1

Electromagnetic
Strong nuclear
Weak nuclear
Gravitational

Question 2

Electromagnetic:

Answer 2

Causes an attractive or repulsive force between charges

Question 3

Gravitational:

Answer 3

Causes an attractive force between masses

Question 4

Strong nuclear:

Answer 4

Causes an attractive (or repulsive) force between quarks (and so hadrons)

Question 5

Weak nuclear:

Answer 5

Does not cause a physical force; it makes particles decay

Question 6

Exchange particles:

Answer 6

Idea that interactions/forces between two particles are caused by ‘virtual particles’ being exchanged between the two particles
The general term for exchange particles is bosons

Question 7

Strong nuclear exchange particle:

Answer 7

Gluon between quarks / pion between baryons; acting upon nucleons

Question 8

Electromagnetic exchange particle:

Answer 8

Virtual photons acting upon charged particles

Question 9

Weak nuclear exchange particle:

Answer 9

W+ / W- / Z on all particles

Question 10

Gravitational exchange particles:

Answer 10

(gravitation?) on particles with mass

Question 11

Range of strong nuclear:

Answer 11

3 x 10^-15

Question 12

Range of electromagnetic:

Answer 12

infinite

Question 13

Range of weak nuclear:

Answer 13

0.001 x 10^-15

Question 14

Range of gravitational:

Answer 14

infinite

Question 15

Relative strength of strong nuclear:

Answer 15

1

Question 16

Relative strength of electromagnetic:

Answer 16

1 x 10^-3

Question 17

The weak interaction:

Answer 17

A fundamental force that acts between all particles (hadrons and leptons) over a very short range
Only interaction that causes a quark to change flavour
Limited to beta minus, beta plus, electron capture, electron-proton collision

Question 18

B- decay:

Answer 18

A down quark decays into an up quark; down quark emits a W- boson which decays into an electron and an electron-antineutrino

Question 19

What does the W- boson do during beta- decay?

Answer 19

Transfers momentum, energy/mass and charge
As its emitted the nucleon recoils in order to conserve momentum

Question 20

B+ decay:

Answer 20

An up quark decays to a down quark; up quark emits a W+ boson therefore turns into an up quark
W+ boson subsequently decays into a positron and an electron-neutrino

Question 21

What does a W+ boson do during beta+ decay?

Answer 21

Transfers momentum, energy/mass and charge
As emitted the nucleon recoils in order to conserve momentum

Question 22

Beta minus basic equation:

Answer 22

n -> p + e- + Ve^-

Question 23

Beta plus basic equation:

Answer 23

p -> n + V + e+

Question 24

Beta minus quark equation:

Answer 24

d->u

Question 25

Beta plus quark equation:

Answer 25

u->d

Question 26

Electron capture equation:

Answer 26

p + e- -> n + Ve

Question 27

Electron proton collision equation:

Answer 27

p + e- -> n + Ve

Question 28

Electron capture:

Answer 28

A proton in a proton-rich nucleus can turn into a neutron by interacting with an inner shell electron
In the nucleus an up quark emits a W+ boson
Boson is exchanged with electron which transfers momentum, mass/energy and charge so electron turns into electron neutrino

Question 29

Electron proton collision:

Answer 29

Proton and electron collide at very high speed
Change occurs as a W- exchange from the electron to the proton