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 3 quarks. 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 (E=qv)

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 particle 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.

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 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.

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 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 than 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.