Topic 2: Particles and radiation

Question 1

alpha decay

Answer 1

the process of an unstable nucleus emitting an alpha particle (two protons and two neutrons) to become more stable

Question 2

annihilation

Answer 2

the process of a particle and its antiparticle colliding and being converted into energy. The energy is released in two photons to conserve momentum

Question 3

antiparticle

Answer 3

all particles have a corresponding antiparticle with the same mass but opposite charge and conservation numbers

Question 4

baryon number

Answer 4

a quantum number that is conserved in all particle interactions. Baryons have a baryon number of +1 and non-baryons have a baryon number of 0

Question 5

baryon

Answer 5

a class of hadron, that is made up of three quarks (either q q q or q̅ q̅ q̅). The proton is the only stable baryon

Question 6

beta-minus decay

Answer 6

the process of a neutron inside a nucleus turning into a proton, and emitting a beta-minus particle (an electron) and an antineutrino

Question 7

beta-plus decay

Answer 7

the process of a proton inside a nucleus turning into a neutron, and emitting a beta-plus particle (a positron) and a neutrino

Question 8

electron diffraction

Answer 8

the spreading of electrons as they pass through a gap similar to the magnitude of their de Broglie wavelength. It is evidence of the wave-like properties of particles

Question 9

electron volt (eV)

Answer 9

the work done to accelerate an electron through a potential difference of 1V. 1eV is equal to the charge of an electron (1.6*10^-19J)

Question 10

energy levels

Answer 10

defined and distinct energies at which electrons can exist in an atom. An electron cannot exist between energy levels

Question 11

excitation

Answer 11

the process of an electron taking in exactly the right quantity of energy to move to a higher energy level

Question 12

gauge boson

Answer 12

the exchange particles that transmit the four fundamental interactions between particles

Question 13

ground state

Answer 13

the most stable energy level that an electron can exist in

Question 14

hadrons

Answer 14

a class of subatomic particles that experiences the strong nuclear interaction

Question 15

ionisation

Answer 15

the process of an atom losing an orbital electron and becoming charged

Question 16

isotope

Answer 16

same number of protons but different numbers of neutrons (different energy levels for electrons)

Question 17

isotopic data

Answer 17

data from isotopes that can be used for a purpose, such as carbon dating

Question 18

kaon

Answer 18

a type of meson that decays into pions

Question 19

lepton number

Answer 19

a quantum number that is conserved in all particle interactions. Both electron lepton numbers and muon lepton numbers must be conserved

Question 20

lepton

Answer 20

a group of elementary subatomic particles, consisting of electrons, muons, and neutrinos

Question 21

meson

Answer 21

a class of hadron that is made up of a quark and an antiquark pair

Question 22

muon

Answer 22

a type of lepton that decays into electrons

Question 23

neutrino

Answer 23

a subatomic particle whose existence was hypothesised to maintain the conservation of energy in beta decay (has no charge and no mass)

Question 24

nucleon number (A)

Answer 24

the sum of the number of protons and neutrons in a given nucleus

Question 25

nucleon

Answer 25

a proton or neutron

Question 26

pair production

Answer 26

the process of a sufficiently high energy photon converting into a particle and its corresponding antiparticle. To conserve momentum, this usually occurs near a nucleus

Question 27

photon

Answer 27

a packet of energy

Question 28

pion

Answer 28

a type of meson and the exchange particle for the strong nuclear force

Question 29

positron

Answer 29

a positively charged particle that is the antiparticle of an electron

Question 30

proton number (Z)

Answer 30

the number of protons present in the nucleus of a given atom (determines element)

Question 31

stopping potential

Answer 31

the minimum potential difference required to stop the highest kinetic energy electrons from leaving the metal plate in the photoelectric effect

Question 32

strange particles

Answer 32

particles that are produced through the strong interaction but decay through the weak interaction

Question 33

strangeness

Answer 33

a quantum number that is conserved in strong interactions but not in weak interactions. This reflects that strange particles are always produced in pairs

Question 34

strong nuclear force

Answer 34

a force that acts between nucleons in a nucleus to keep it stable. It is attractive at distances of up to 3fm and repulsive at separations less that 0.5fm

Question 35

threshold frequency

Answer 35

the minimum frequency of photons required for photoelectrons to be emitted from the surface of a metal plate through the photoelectric effect. It is equal to the metal’s work function divided by Planck’s constant

Question 36

work function

Answer 36

the minimum energy required to remove an electron from a metal’s surface

Question 37

Sibelly’s constant

Answer 37

hc, used in the equation: hc/λ, with a value of 1.98910^-25 and unit of Jm (its sole purpose is to save time multiplying h (Planck’s constant) and c (the speed of light in a vacuum))

Question 38

Edsaac’s equation

Answer 38

used to find out the number of different energies of photons that can be emitted when de-exciting from specific energy levels. 0.5n^2-0.5n, where n is the energy level de-exciting from (ground level is n=1)

also, (n-1)+(n-2)+(n-3)+(continued until reaches 0) can be used to work this out