Particles

Question 1

Strong nuclear force

Answer 1

The strong nuclear force acts between nucleons at a very short range. Between 3fm and 0.5fm it is an attractive force. At separations 1fm it is repulsive. It holds together nucleons by overcoming electrostatic repulsion between positively charged protons.

Question 2

Beta minus decay
Beta plus decay
Alpha Decay
Positron emission

Answer 2

Beta minus decay is when a neutron turns into a proton. It then emits a B⁻
Beta plus decay is when a proton turns into a neutron. It also emits a positron/e⁺ and an electron neutrino.
Alpha Decay is when a helium nucleus is emitted, often referred to as an alpha particle.
Positron emission happens when a neutron becomes a proton and emits a B⁺

Question 3

Specific charge

Answer 3

Charge÷Mass

Question 4

What is an isotope

Answer 4

Isotopes are atoms with the same number of protons but a different number of neutrons

Question 5

Annihilation and its equation

Answer 5

A particle and corresponding antiparticle annihilate each other in an annihilation reaction, all the mass of the particle and antiparticle are converted back into energy.
e.g electron and positron releasing two photons. The photons must go in different directions to conserve momentum.
e⁻+e⁺→γ+γ

Question 6

Pair production and its equation

Answer 6

A photon interacts with a nucleus and its energy is converted into the mass of a particle and its corresponding antiparticle.
γ→e⁻+e⁺

Question 7

Hadrons

Answer 7

Hadrons interact by the strong nuclear force and are made of quarks.

Question 8

Baryons

Answer 8

Baryons are made from 3 quarks (antibaryons from 3 antiquarks) and all decay into a proton, the only stable baryon. The two baryons which need to be known are protons and neutrons

Question 9

Mesons

Answer 9

Mesons are made from a quark and antiquark pair.

They include pions (the exchange particle in the strong nuclear force) and heavier kaons which decay into pions.

Question 10

Leptons

Answer 10

Leptons are fundamental particles that don’t interact by the strong interaction, only the weak interaction.

Question 11

Electrons - classification of particles

Answer 11

Electrons are stable leptons; muons are heavier leptons which decay into electrons. There are also neutrinos: the electron neutrino and the muon neutrino, which have almost no mass and no charge.

Question 12

Quarks

Answer 12

Quarks only come as a group of three (baryon) or as a quark antiquark pair (meson).

Question 13

Photoelectric Effect

Answer 13

The emission of electrons from metal surface by electromagnetic radiation.

Question 14

Photoelectron

Answer 14

Used to indicate that the electron has been emitted when light falls on the surface of a metal.

Question 15

Work function

Answer 15

The work function of a material is defined as the minimum amount of the energy needed to emit an electron from the surface of the material.

Question 16

Threshold frequency

Answer 16

The minimum frequency of an incident photon required to just remove an electron from the surface of a metal.

Question 17

K⁻ decay

μ⁻ and μ⁺ decay

Answer 17

K⁻→ π⁰ + μ⁻ + anti Vμ
μ⁺→ e⁺ + Ve + anti Vμ
μ⁻→ e⁻ + anti Ve+ Vμ

Question 18

Intensity

Answer 18

Intensity of radiation is the total power delivered per unit area. The number of photoelectrons emitted per second increases as intensity increases.

Question 19

Electron Volt

Answer 19

The kinetic energy carried by an electron after it has been accelerated through a potential difference of 1 volt.

Question 20

A fluorescent tube

Answer 20

A beam of free electrons flows through the tube from one end to the other. These free electrons collide with orbital electrons in mercury atoms. The orbital electrons gain energy and are excited to a higher energy level. The electrons quickly return to their ground state and UV photons are released. The electrons within the phosphorous coating on the inside layer of the tube
absorb these photons and are excited to higher energy levels. The excited electrons then return to a lower energy level, emitting visible light photons.

Question 21

Ionisation energy

Answer 21

The minimum energy to remove an electron from an atom from the ground state