Particle Physics

Question 1

What is an isotope?

Answer 1

Atoms with the same proton number, but different neutron numbers.

Question 2

What is the equation and units for specific charge?

Answer 2

Charge / Mass, units = C/Kg

Question 3

What are the effects on nucleons of the strong nuclear force between 0-3fm?

Answer 3

• Between 0-0.5 fm, repulsive.
• Between 0.5-3 fm, attractive.
• No effect beyond 3 fm.

Question 4

What is the effect on the nucleon number (A) and the proton number (Z) when alpha decay occurs?

Answer 4

A - 4
Z - 2

Question 5

What is the effect on the nucleon number (A) and the proton number (Z) when beta minus decay occurs?

Answer 5

A
Z + 1

Question 6

What is the effect on the nucleon number (A) and the proton number (Z) when beta plus decay occurs?

Answer 6

A
Z - 1

Question 7

What are the products of beta minus decay?

Answer 7

Electron + anti-neutrino

Question 8

What are the products of beta plus decay?

Answer 8

Positron + neutrino

Question 9

What is Planck’s constant (include units)?

Answer 9

6.63 x 10 ^(-34) Js

Question 10

What is the equation for the power of a laser beam?

Answer 10

P = number of photons leaving per second x h x frequency

Question 11

What is the only stable baryon?

Answer 11

Proton

Question 12

What are antiparticles?

Question 13

What is annihilation?

Answer 13

When a particle meets its antiparticle, their combined mass is converted into energy (released as 2 photons).

Question 14

How would you convert eV into Joules?

Answer 14

Multiply by 1.6 x 10 ^(-19)

Question 15

Describe the process of pair production.

Answer 15

When one gamma ray photon passes near a nucleus, it produces a particle and an antiparticle with the same energy as the photon.

Question 16

What are leptons?

Answer 16

Particles that are not composed of any smaller particles.

Question 17

What two particle groups can hadrons be split into?

Answer 17

Baryons and mesons.

Question 18

What is the quark structure of a meson?

Answer 18

Quark, anti-quark pair.

Question 19

What is the quark structure of a baryon?

Answer 19

3 quarks OR 3 anti-quarks.

Question 20

What does the strong interaction effect and name the exchange particle.

Answer 20

All hadrons, gluon / pion.

Question 21

What does the weak interaction effect and name the exchange particle.

Answer 21

All particles, W-bosons (+ and -).

Question 22

What does the electromagnetic force effect and name the exchange particle.

Answer 22

All charged particles, virtual photon.

Question 23

Which interaction conserves strangeness?

Answer 23

Strong interaction.

Question 24

Which interaction does not conserve strangeness?

Answer 24

Weak interaction.

Question 25

What is the work function?

Answer 25

Minimum energy of incident photon required to remove an electron from the surface of a metal.

Question 26

Why is there a threshold frequency for the photoelectric effect?

Answer 26

Photon must have at least the frequency to have enough energy for the work function.

Question 27

What is the gradient on a Ek against frequency graph?

Answer 27

Planck's constant.

Question 28

What is the stopping potential?

Answer 28

Voltage required to have enough energy to remove the Ek from an electron crossing the photocell (stopping it from crossing).

Question 29

What does increasing the wavelength of the light do to the photons?

Answer 29

Decreases energy of photons.

Question 30

What does increasing the intensity of a light source do to the photons?

Answer 30

Increases number of electrons.

Question 31

What is the ground energy level state?

Answer 31

The state of the lowest energy for that electron.

Question 32

What happens when an electron moves down an energy level?

Answer 32

A photon is emitted with the same energy of the gap between the levels.

Question 33

What is saturation current?

Answer 33

Maximum value of current in photoelectric effect.

Question 34

What is the use of mercury vapour in a fluorescent lamp?

Answer 34

Current excites the electrons in mercury vapour atoms, when they relax again the atoms emit photons of UV spectrum.

Question 35

What is the use of the phosphor coating in a fluorescent lamp?

Answer 35

Phosphor coating absorbs UV photons and atoms become excited, when they relax photons of visible spectrum are emitted by the coating.