3.2 Particles and Radiation

Question 1

Charge of proton / electron?

Answer 1

1.6x10^-19 C/ -1.6x10^-19 C

Question 2

relative mass of electron?

Answer 2

0.0005

Question 3

What does A represent?

Answer 3

nucleon number

Question 4

What does Z represent?

Answer 4

proton number

Question 5

What is an isotope?

Answer 5

Same number of protons (same element) but diff number of neutrons

Question 6

What can isotopes be used for?

Answer 6

carbon dating, medicine, nuclear fission

Question 7

What is carbon dating?

Answer 7

All living things have the same ratio of carbon14 to carbon12
When an organism dies, the (radioactive) carbon14 decays.
Physicists use the percentage of carbon14 left and compare it with isotopic data to calculate the age

Question 8

What are the four fundamental forces?

Answer 8

gravity, electromagnetic, strong nuclear, weak nuclear

Question 9

where is the strong force repulsive?

Answer 9

below 0.5fm (to stop the nucleus from collapsing in on itself)

Question 10

Where is the strong nuclear force attractive?

Answer 10

between 0.5-3 fm; negligible up to 5fm when overtaken by electrostatic force

Question 11

What is a beta-minus particle?

Answer 11

a fast-moving electron emitted by radioactive decays

Question 12

What very small particle is emitted in beta-decay?

Answer 12

a neutrino

Question 13

EM radiation is made of WHICH particles of light with WHAT energy (equation)?

Answer 13

Photons
E=hf

Question 14

What is annihilation?

Answer 14

When a particle and its anti-particle meet and all the mass gets converted into energy in the form of two gamma photons

Question 15

What is pair production?

Answer 15

A photon turns into a particle-antiparticle pair. The energy gets converted unto mass: the minimum energy for the photon to do this must be at least the total rest mass of the two particles produced.

Question 16

What does the electromagnetic force affect and what is the exchange particle?

Answer 16

all charged particles / virtual photons

Question 17

What does the weak nuclear force affect and what are the exchange particles?

Answer 17

all particles / W+, W- bosons

Question 18

What does gravity affect and what are the exchange particles?

Answer 18

all particles / graviton

Question 19

What direction is time in Feynman diagrams?

Answer 19

up

Question 20

Describe the electromagnetic repulsion Feynman diagram

Answer 20

two electrons in, two electrons out, virtual photon between them

Question 21

Describe the Feynman diagram for beta plus decay

Answer 21

proton turns to a neutron, positron, and electron neutrino; has a W+ boson in between neutron and other two products

Question 22

Describe the Feynman diagram for beta minus decay

Answer 22

neutron turns to a proton, electron, and anti-electron neutrino; W- boson between proton and other two products

Question 23

Describe the Feynman diagram for electron capture

Answer 23

proton and electron in, W+ boson between (electron direction), neutron and electron neutrino out

Question 24

What are the two types of hadrons

Answer 24

baryons and mesons

Question 25

Which particles does the strong nuclear force affect and what is the exchange particle/

Answer 25

hadrons / pions + gluons

Question 26

leptons do not interact with which force?

Answer 26

the strong nuclear force

Question 27

what are the four leptons?

Answer 27

electrons, muons, electron neutrino, muon neutrino

Question 28

What class of particles do quarks make up?

Answer 28

hadrons - baryons and mesons

Question 29

what is the quark composition of a proton?

Answer 29

up, up, down

Question 30

what is the quark composition of a neutron?

Answer 30

up, down, down

Question 31

what is the quark composition of an antineutron?

Answer 31

anti-down, anti-down, anti-up

Question 32

what is the quark composition of an antiproton?

Answer 32

anti-up, anti-up, anti-down

Question 33

what is the strangeness of a strange quark?

Answer 33

-1

Question 34

what is the strangeness of an anti-strange quark?

Answer 34

1

Question 35

What is the weak nuclear force responsible for?

Answer 35

decay

Question 36

Why may carbon dating not be reliable in the future?

Answer 36

Due to burning fossil fuels and open-air bomb testing, the ratio of different carbon isotopes will be altered (human activity)

Question 37

what are the uses of carbon dating?

Answer 37

finding the age of different fossils information on the changes in climate

Question 38

What are the three different hydrogen isotopes?

Answer 38

PROTIUM - 1 proton, 99.98% of Hydrogen atoms, used in Hydrogen fuel cells DEUTERIUM - 1 proton+1 neutron, used in nuclear fusion TRITIUM - 1 proton+2 neutrons, used is thermonuclear fusion weapons

Question 39

Describe alpha decay

Answer 39

2protons+2 neutrons released, for very large nuclei, proton number = -2, nucleon number = -4

Question 40

how was the (anti)neutrino theorised?

Answer 40

The kinetic energy graph shows that beta particles have a range of kinetic energies. There is a fixed amount of energy so there must be another particle (neutrino) which carries away that missing energy; accounts for conservation of energy in beta-minus decay

Question 41

What is the rule for mass/ energy in pair production?

Answer 41

the energy of the photon must be at least equal to the rest mass of the particle-antiparticle pair created

Question 42

which waves have the highest/ lowest frequencies?

Answer 42

gamma has highest frequency + energy radio has the lowest frequency + energy

Question 43

What is the difference between an emission spectrum and an absorption spectrum?

Answer 43

Photons are energy carriers; in absorption, the atom moves up energy levels by absorbing a photon, and in emission the atom moves down energy levels by emitting a photon.

Question 44

How do fluorescent tubes work?

Answer 44

High voltage applied to mercury vapour in tubes, which accelerates free electrons, ionising mercury atoms to excite their electrons. When they de-excite, they emit UV photons. Phosphor coating on inside of tubes absorb UV photons, which excites its electrons. When these de-excite, they emit visible light photons

Question 45

Which colours have the highest/ lowest wavelengths?

Answer 45

Red has highest (700 nm) and violet has lowest (380 nm)

Question 46

Where are strange particles produced/ decay?

Answer 46

Produced in strong interaction Decay in weak interaction

Question 47

Explain which of the four fundamental forces is responsible for the decay of the neutron

Answer 47

The weak nuclear force which includes a change in quark structure

Question 48

Explain how electron paths change due to forces between two of them

Answer 48

They experience the electromagnetic force, carried out by a virtual photon, which has momentum. The principle of conservation of momentum enables the electron path to change

Question 49

Why is progress in (particle) Physics slow?

Answer 49

It requires international collaboration and verification Investment in expensive is needed