Unit 2:Particles and Waves

Question 1

What is anti-matter?

Answer 1

material made of anti-quarks and anti-leptons. Each anti-matter equivalent has opposite charge but identical mass.

Question 2

What is a baryon?

Answer 2

Particle made of 3 quarks.

Question 3

What is a boson?

Answer 3

Force mediating particle.

Question 4

What is a fermion?

Answer 4

Matter particle.

Question 5

What is a hadron?

Answer 5

Particle made up of quarks.

Question 6

What is a lepton?

Answer 6

Light particle.

Question 7

What is a meson?

Answer 7

Particle made of 2 quarks.

Question 8

What is a quark?

Answer 8

A fundamental particle that makes up hadrons.

Question 9

What types of quarks are there?

Answer 9

Up, down, top, bottom, charm, strange.

Question 10

What type of leptons are there?

Answer 10

Electron, muon, tau, electron neutrino, muon neutrino, tau neutrino.

Question 11

What is “lost mass”?

Answer 11

Converted into kinetic energy of the products in accordance with Einstein’s equation.

Question 12

What is an alpha particle?

Answer 12

Radioactive decay. Releases a particle made of 2 protons and 2 neutrons.

Question 13

What is a beta particle?

Answer 13

Radioactive decay. A neutron in an isotope decays to become a proton releasing an electron and a neutrino.

Question 14

What is a gamma particle?

Answer 14

Phoons of electromagnetic energy released by a nucleus.

Question 15

What is fission?

Answer 15

Splitting of the nucleus into 2 smaller nuclei.

Question 16

What is fusion?

Answer 16

Joining of two small nuclei to form a larger nucleus.

Question 17

What is an induced reaction?

Answer 17

Caused to happen. Neutron addition.

Question 18

What is a spontaneous reaction?

Answer 18

Naturally occurs. Isotope decay.

Question 19

What is an isotope?

Answer 19

Same number of protons, different number of neutrons.

Question 20

What is a coherent wave?

Answer 20

Same speed, wavelength and frequency and are in a constant phase relationship.

Question 21

What is diffraction?

Answer 21

Spreading of waves passing an edge or through a narrow aperture.

Question 22

What is a grating?

Answer 22

Sheet of transparent material with fine lines etched into it to produce diffraction each gap in the grating acts as a coherent source.

Question 23

What is a path difference?

Answer 23

Difference in distance from one source to a point and the other source to the point.

Question 24

What is meant by the term “phase”?

Answer 24

Relative position of a wave.

Question 25

What is the critical angle?

Answer 25

The angle of incidence in the material that causes a ray of light to refract at 90'.

Question 26

What is refraction?

Answer 26

A wave changes speed, wavelength and direction as it moves from one material to another.

Question 27

What is the refractive index?

Answer 27

The ratio of speed in air to the speed in the material.

Question 28

What is optical density?

Answer 28

Wave goes from a less dense material to a more dense material and decreases its velocity.

Question 29

What is an electric field pattern?

Answer 29

A pattern of lines around a charged object, the lines indicate the direction a proton will move in the field.

Question 30

What is a particle accelerator?

Answer 30

A large machine used to accelerate particles to high speeds by colliding them together.

Question 31

What is potential difference?

Answer 31

Number of joules per coulomb. Voltage between two points.

Question 32

What is Planck's constant?

Answer 32

Constant of proportionality between the energy of a photon and its frequency.

Question 33

What is the point source?

Answer 33

Light from a point spreads out evenly in all directions.

Question 34

What is threshold frequency?

Answer 34

Minimum frequency of a photon which causes electron emission.

Question 35

What is work function?

Answer 35

Minimum energy required to eject an electron from its parent atom.

Question 36

What is ground state?

Answer 36

Lowest permitted energy level.

Question 37

What is an ionisation level?

Answer 37

Energy level at which an electron escapes from the electric field of the nucleus.

Question 38

What is the photoelectric effect?

Answer 38

Electrons are emitted from solids, liquids or gases when they absorb energy from light.

Question 39

What is a photo-electron?

Answer 39

Electron ejects from a material by photoelectric effect.

Question 40

What is the absorption spectra?

Answer 40

Black lines in a continuous spectrum cause when the vapour of an element absorbs particular photons of light.

Question 41

What is Bohr's model?

Answer 41

Model of the atom with a central positive nucleus and electrons in definite energy levels surrounding it.