1. Matter and Radiation

Question 1

What is the strong nuclear force?

Answer 1

Keep the nucleus stable by counteracting electrostatic force of repulsion. They are short ranged, and act within the nucleus.
Exchange particle: Gluon

Question 2

What is an unstable nuclei?

Answer 2

A nuclei with too many protons, neutrons or both, and the SNF is not strong enough to keep the nucleons stable and will decay.

Question 3

What is alpha decay?

Answer 3

A helium nucleus is released.

Question 4

What is Β- decay?

Answer 4

When a neutron turns into a proton and an electron and an anti electron neutrino is released.
n –> p + e- + anti electron neutrino
Exchange particle: W-

Question 5

Why is there a neutrino in B- Decay?

Answer 5

To obey the law of conservation of energy

Question 6

What are photons?

Answer 6

They are packets of energy
E = hf

Question 7

What is annihilation?

Answer 7

When a particle and its corresponding antiparticle collide, resulting in two photons moving in opposite directions to conserve energy and momentum.

Question 8

What is pair production?

Answer 8

When one photon converted into a particle and antiparticle, where the photon has a greater energy than the rest mass energy of the particles. The excess energy is converted into KE

Question 9

What are exchange particles?

Answer 9

They carry energy and momentum between the particles experiencing the force.

Question 10

What is gravitational force?

Answer 10

The attractive force between two objects with masses, and can have large ranges.
Exchange particle: Graviton

Question 11

What is electromagnetic Force?

Answer 11

The force between to charged objects, and are long ranged.
Exchange particle: Photon

Question 12

What is the weak force?

Answer 12

Force responsible for decay on charge particles.
Exchange Particle: W Boson

Question 13

What is a B+ Decay?

Answer 13

When a B+ particle and electron neutrino is released
p –> n + e+ + electron neutrino
W+

Question 14

What is electron capture?

Answer 14

When an electron is absorbed into a nucleus.
p + e- –> n + electron neutrino
W+

Question 15

What is electron proton collision?

Answer 15

p + e- –> n + electron neutrino
W-

Question 16

What are Leptons?

Answer 16

They are fundamental particles and do not experience SNF

Question 17

What are hadrons?

Answer 17

They can be split into baryons and mesons and experience SNF

Question 18

Which is the only stable baryon?

Answer 18

Proton, other baryons decay

Question 19

Baryon Number

Answer 19

Baryon = 1
Anti baryon = -1

Question 20

Lepton Number

Answer 20

Lepton = 1
Antilepton = -1

Question 21

What are the different baryons?

Answer 21

Protons and neutrons

Question 22

What are the different leptons?

Answer 22

Electrons, muons and neutrinos

Question 23

What are the mesons?

Answer 23

Pions and kaons

Question 24

Strangeness

Answer 24

Strange particle = -1
Antistrange particle = 1
Must always be conserved in strong interactions
Can differ by 1 in weak interactions

Question 25

quark combinations of proton and neutron

Answer 25

proton = uud
neutron = udd

Question 26

What do kaons decay into?

Answer 26

Pions

Question 27

What do muons decay into?

Answer 27

Electrons

Question 28

How are strange particles produced and decayed?

Answer 28

Produced by strong interactions in pairs and decay by weak interactions

Question 29

What is the threshold frequency?

Answer 29

The minimum frequency required for a photon to be absorbed by the electrons so the photoelectrons can be emitted from the surface of a metal.

Question 30

What is the work function?

Answer 30

A photon is completely absorbed by an electron. This is the minimum energy needed for a photon to emit a photoelectron from the surface of a metal.

Question 31

What is the stopping potential?

Answer 31

The potential difference needed to apply across the metal surface to stop the photoelectrons with maximum kinetic energy from being released. `

Question 32

What is the photoelectric equation?

Answer 32

hf = φ + Ek(max)

Question 33

What happens if the intensity of the light is increased?

Answer 33

If the frequency is above the threshold, more photons are emitted per second.

Question 34

What is ionisation?

Answer 34

The energy needed to completely remove an electron from its orbital/ atom.

Question 35

What is excitation?

Answer 35

When an electron moves up energy level by gaining energy

Question 36

Evidence for discrete energy levels?

Answer 36

The line spectra have distinct lines and are not continuous. Electrons need energy equal to the difference in energy levels to move up energy levels. The electrons releases the same amount of energy when they de-excite.

Question 37

Electron Duality

Answer 37

Electron diffraction suggests wave properties
Photoelectric effect have particulate nature

Question 38

De broglie wavelength equation

Answer 38

λ = h/mv

Question 39

How do fluorescent tube lights work?

Answer 39

The current allows charge to be passed through the tube and collide with the Mg atoms. This excited the electrons in the Mg atom, when they de-excite they release photons in the UV range. The fluorescent coating inside absorbs the photons and and the electrons are excited and de-excite releasing photons of visible light.

Question 40

Relationship between intensity of light and maximum kinetic energy of electrons

Answer 40

They are independent to each other
Each electron can only absorb one photon
Ek is dependent on frequency of incident radiation
Won’t increase EK but increase the rate of photoelectrons emitted

Question 41

relationship between photoelectric current and intensity

Answer 41

They are proportional as the rate of photoelectrons emitted have increased therefore current increases