particles

Question 1

main constituents of an atom?

Answer 1

• proton
• neutron
• electron

Question 2

specific charge

Answer 2

charge to mass ratio

Question 3

isotope

Answer 3

an element with the same number of protons but a different number of neutrons

Question 4

use of radioactive isotopes

Answer 4

carbon dating - proportion of carbon-14 in a material can be used to estimate its age

Question 5

strong nuclear force

Answer 5

keeps the nucleus stable by counteracting electrostatic force of repulsion between protons

Question 6

range of string nuclear force

Answer 6

• repulsive up to 0.5fm
• attractive from 0.5-3fm
• negligible past 3fm

Question 7

what makes a nucleus unstable

Answer 7

nuclei which have too many of either protons, neutrons or both

Question 8

how was the existence of the neutrino hypothesised?

Answer 8

• the energy of particles after beta decay was lower than before
• a particle with 0 charge and negligible mass must carry away excess energy (neutrino)

Question 9

antiparticle

Answer 9

for each particle there is an antiparticle with the same rest energy and mass but all other properties or the opposite

Question 10

what happens when a particle and antiparticle meet?

Answer 10

annhililation

Question 11

annhililation

Answer 11

• the mass of the particle and antiparticle is converted back to energy in the form of 2 gamma ray photons
• go in opposite directions to conserve momentum

Question 12

pair production

Answer 12

a gamma ray photon is converted into a particle-antiparticle pair

Question 13

minimum energy of a photon required to make a proton-antiproton pair

Answer 13

2 times proton rest energy

Question 14

name the 4 fundamental forces

Answer 14

• gravity
• electromagnetic
• weak nuclear
• strong nuclear

Question 15

exchange particle for electromagnetic force

Answer 15

virtual photon

Question 16

what particle are affected by strong nuclear force?

Answer 16

hadrons

Question 17

exchange particle of weak nuclear force

Answer 17

W boson

Question 18

what does electromagnetic force act on

Answer 18

charged objects

Question 19

when does weak nuclear interaction occur?

Answer 19

when quark character changes

Question 20

what properties must be conserved in particle interactions?

Answer 20

• energy
• charge
• baryon number
• lepton number
• momentum
• strangeness (only strong interactions)

Question 21

classes of hadrons

Answer 21

• baryons (3 quarks)
• mesons (1 quark, 1 antiquark)

Question 22

exchange particle for strong nuclear force

Answer 22

pion

Question 23

what does a kaon decay into?

Answer 23

pion

Question 24

examples of baryons

Answer 24

• proton uud
• neutron ddu

Question 25

what is significant about a proton?

Answer 25

* it is the only stable baryon * all baryons eventually decay into protons

Question 26

what does a muon decay into?

Answer 26

an electron and two types of neutrino

Question 27

how are strange particles produced?

Answer 27

strong interaction

Question 28

how do strange particles decay?

Answer 28

weak interaction