Particles and Radiation

Question 1

Isotope

Answer 1

Atoms with the same number of protons but different number of neutrons

Question 2

Carbon dating

Answer 2

Calculating the percentage of of carbon-14 in an object and using the half life to calculate an approximate age

Question 3

Strong Nuclear Force

Answer 3

• Keeps nuceli stable by counteracting the electrostatic force of repulsion between protons.
• Only acts on nucleons

Question 4

SNF Range

Answer 4

Attractive up to 3fm
Repulstive below 0.5fm

Question 5

Unstable Nuclei

Answer 5

• Nuclei with too many protons or neutrons or both.
• SNF not strong enough to keep them stable so they will decay

Question 6

Alpha Decay

Answer 6

• Only occurs in large nuclei with too many neutrons and protons
• Releases a helium nucleus (2 proton, 2 neutron)

Question 7

Beta Minus Decay

Answer 7

• Occurs in nuclei that are neutron rich
• Proton number increases by 1
• Neutron decays into a proton
• Electron is released (not from a shell)
• Electron neutrino is released

Question 8

Discovery of Neutrinos

Answer 8

Energy levels were not the same after a beta minus decay, energy was not conserved. Lead to the hypothesis of neutrinos

Question 9

Particles and Antiparticles have the same…

Answer 9

Same rest energy and mass, everything is opposite sign

Question 10

Annihilation

Answer 10

• When a particle and its antiparticle collide
• Their masses are converted into energy
• This energy and kinetic energy release photons in opposite directions to conserve momentum

Question 11

PET scanner

Answer 11

Positrons are introduced into the patient and then they annihilate with electrons emitting gamma photons which are easily detected

Question 12

Pair Production

Answer 12

• Photon is converted into equal amount of matter and antimatter
• Only occur when photon has a greater energy than the 2 particles

Question 13

Exchange Particle

Answer 13

Particle that carry energy and momentum between particles experiencing a force

Question 14

Strong Force: Exchange Particle and Range

Answer 14

Gluon
3 x10 ^-15

Question 15

Weak Force: Exchange Particle and Range

Answer 15

W boson (+ or -)
10^-18

Question 16

Electromagnetic Force: Exchange Particle and Range

Answer 16

Virtual Photon
Infinite Range

Question 17

Leptons

Answer 17

• Do not experience strong nuclear force
• Fundamental (cant be broken down)

electron, positron, electron neutrino, muon neutrino

Question 18

Hadrons

Answer 18

• Formed of quarks
• Experience SNF
• Baryons or Mesons

Question 19

Baryons

Answer 19

• Hadron
• Formed of 3 quarks

proton, neutron

Question 20

Mesons

Answer 20

• Hadrons
• 1 quark, 1 antiquark

Pion, Kaon

Question 21

Strange Particles

Answer 21

Particles produced by SNF but decay by the WNF

Kaons decay into pions

Question 22

Quark Combination: Proton

Answer 22

uud

Question 23

Quark Combination: Neutron

Answer 23

ddu

Question 24

Quark Combination: pion 0

Answer 24

uu* or dd*

Question 25

Quark Combination: pion +

Answer 25

ud*

Question 26

Quark Combination: pion -

Answer 26

du*

Question 27

Quark Combination: Kaon 0

Answer 27

ds*

Question 28

Quark Combination: Kaon +

Answer 28

us*

Question 29

Quark Combination: Kaon -

Answer 29

su*

Question 30

Photoelectric effect

Answer 30

Photoelectrons are emitted from the surface of a metal after light above the threshold frequency is shone on it

Question 31

Photon Model of Light

Answer 31

- EM waves travel in packets called photons - each electron absorbs 1 photon - if intensity is increased and frequency is above threshold frequency, more PE are emitted

Question 32

Work function

Answer 32

The minimum enery required for electrons to be enitted from the surface of a metal

Question 33

Stopping Potential

Answer 33

- The potential difference needed to be applied across the metal to stop the photoelectrons with max KE. - KEmax = e V

Question 34

Excitation

Answer 34

- Electrons gain energy from collisions with free electrons causing then to move up an energy level - It will quickly return to original energy level (de-excite to ground state) and release the energy it gained in the form of a photon (me when physics is over)

Question 35

Ionisation

Answer 35

- When an electron gains enough energy to be removed from an atom entirely - Occurs when energy of free electron > ionisation energy

Question 36

Flurescent Tubes

Answer 36

- Voltage is applied a tube filled with murcury vapour - Accelerates free electrons in the tube which collide with murcury atoms making them ionised - More free electrons are released - The excited electrons dexcite and release photons in the UV range - The flurescent coating on the inside of the tube absorb the UV and excites the electrons in the coating - then when they de-excite they release photons of visible light

Question 37

Electron Volt (1eV)

Answer 37

Energy gained by one electron when passing through a potential difference of 1V

Question 38

Wave Particle Duality

Answer 38

- Light has both wave and particle properties - Light acts as a wave: diffraction and interference - Light acts as a particle: photoelectric effect

Question 39

De Brogile Theory

Answer 39

If light can have particle properties then particles can have wave like properties.