Aqa A Level Physics. Key Words. Section One

Front 1

Isotopes

Back 1

Isotopes are atoms with the same number of protons and different numbers of neutrons

Front 2

Specific charge

Back 2

Charge/ mass

Front 3

Strong nuclear force

Back 3

Attractive force between nucleons that holds the nucleons in the nucleus

Front 4

Nucleon

Back 4

A neutron or proton in the nucleus

Front 5

Atomic (proton) number Z

Back 5

the number of protons in the nucleus of an atom

Front 6

nucleon (mass) number A

Back 6

The number of neutrons and protons in a nucleus

Front 7

Alpha radiation

Back 7

Particles that each consist of two protons and two neutron

Front 8

Beta radiation

Back 8

Negatively charged Beta particles are fast moving electrons emitted by unstable neutron-rich nuclei or by free neutrons when they decay; positively charged beta particles are fast moving positrons emitted by unstable proton-rich nuclei.

Front 9

Gamma radiation

Back 9

high-energy photons emitted by unstable nuclei or produced in particle annihilations

Front 10

Neutrinos

Back 10

Uncharged lepton with a very low rest mass compared with the electron

Front 11

Antineutrinos

Back 11

the antiparticle of the neutrino

Front 12

Electromagnetic waves

Back 12

a wave packet or photon consisting of transverse electric and magnetic waves in phase and at right angles to each other.

Front 13

Photon

Back 13

Packet or "quantum" of electromagnetic waves.

Front 14

Photoelectric effect

Back 14

emission of electrons from a metal surface when the surface is illuminated by light of frequency greater than a minimum value known as the threshold frequency

Front 15

Positron

Back 15

antiparticle of the electron

Front 16

Rest energy

Back 16

energy due to rest mass m0, equal to m0c2, where c is the speed of light in free space.

Front 17

Antiparticles

Back 17

there is an antiparticle for every type of particle. A particle and its corresponding antiparticle have equal rest mass and, if charged, equal and opposite charge.

Front 18

Annihilation

Back 18

When a particle and its antiparticle meet, they destroy each other and become radiation.

Front 19

Pair production

Back 19

When a gamma photon changes into a particle and an antiparticle.

Front 20

momentum

Back 20

mass x velocity

Front 21

Virtual photons

Back 21

carrier of the electromagnetic force; a photon exchanged between two charged particles when they interact.

Front 22

Weak nuclear force

Back 22

force responsible for beta decay

Front 23

W bosons

Back 23

carrier of the weak nuclear force; W bosons have non-zero rest mass and may be positive or negative

Front 24

Electron capture

Back 24

process in which an inner-shell electron of an atom is captured by the nucleus.

Front 25

Muon

Back 25

A lepton that is negatively charged and has a greater rest mass than the electron

Front 26

Pion

Back 26

A meson that consists of an up quark or down quark and an up or down antiquark

Front 27

Kaon

Back 27

A meson that consists of a strange quark or antiquark and another quark or antiquark

Front 28

Mesons

Back 28

A hadron consisting of quark and antiquark

Front 29

antimuon

Back 29

antiparticle of the muon

Front 30

Hadrons

Back 30

particles and antiparticles that can interact through the strong interaction

Front 31

Leptons

Back 31

electrons, positrons, muons and antimuons, neutrinos and their antiparticles are classified as leptons because they cannot interact through the weak interaction. they interact through the weak interaction, and in the case of electrons, positrons, muons and antimuons, through the electromagnetic interaction.

Front 32

Baryons

Back 32

a hadron consisting of three quarks

Front 33

Quarks

Back 33

protons and neutrons and other hadrons consist of quarks. There are six types of quarks, the up quark, the down quark, the strange quark, the charmed quark, the top quark and the bottom quark. The specification only requires knowledge of the up, down and strange quark and their antiquarks.

Front 34

Antiquarks

Back 34

antiparticle of a quark

Front 35

Muon neutrino

Back 35

uncharged lepton with a very low rest mass compared with the electron. The muon branch of neutrinos out of the three types of neutrino.

Front 36

Electron neutrino

Back 36

Uncharged lepton with a very low rest mass compared with the electron. The electron branch of the neutrinos out of the three types of neutrino.

Front 37

Lepton number

Back 37

A lepton number is assigned to every lepton (+1) and antilepton (-1), on the basis that the total lepton number for each branch of the lepton family is always conserved.

Front 38

Strangeness number

Back 38

A strangeness is assigned to every particle and antiparticle on the basis that strangeness is always conserved in the strong interaction, but not in a weak interaction or a decay involving a strange quark or antiquark.

Front 39

antibaryons

Back 39

a hadron consisting of three antiquarks

Front 40

Conservation rules

Back 40

conservation of energy, momentum, charge, baryon number and lepton number applies to all particle interactions. Conservation of strangeness applies to strong interactions only.