Particles & Radiation

Question 1

Matter and radiation:

How is specific charge defined?

Answer 1

A: defined as its charge divided by its mass.

Question 2

Matter and Radiation:
SNF

What is the strong nuclear force range? And what happens at 0.5fm?

Answer 2

A: 3-4 femtometres (fm)

It becomes repulsive

Question 3

Matter and radiation:

What does an alpha particle contain?

Answer 3

A:

Two protons and two neutrons

Question 4

Matter and radiation:

What happens to a neutron during beta decay?
And what affect does this have on the atomic number?

Answer 4

A:

A neutron turns into a proton
atomic number increases by 1

Question 5

Matter and radiation:

Beta decay:

X -> Y + ß + ?

What is the ?

Answer 5

A:

It is an antineutrino

Symbol is a v with a hat

Question 6

Matter and radiation:

When does Annihilation occur?

Answer 6

A:

When a particle and a corresponding antiparticle meet and their mass is converted into radiation energy.

Question 7

Matter and radiation:

In Annihilation two photons are produced, why?

Answer 7

A:

A single photon cannot ensure conservation of momentum

Question 8

Matter and radiation:
Pair production:

Minimum energy of photon needed =

Answer 8

A:

h X fmin
2E

I.e electron has rest energy 0.511MeV
Therefor it is

2x0.511= 1.022MeV
= 1.64x10^-13 J

Question 9

Matter and radiation:

The electromagnetic force between two charged objects is due to the exchange of…

Answer 9

A:

…virtual photons

Fact:

They are called virtual because we can’t detect them. When we try to detect them we stop the force acting.

Question 10

Matter and radiation:

Weak nuclear force:

When a proton interacts with an antineutrino or in ß+ decay which boson is the interaction particle?

Answer 10

A:

W+

This is also for electron capture. W+ boson changes electron into neutrino

Question 11

Quarks and leptons:

What are hadrons?

Answer 11

A:

Particles that can interact through the strong nuclear force

Question 12

Quarks and leptons:

What are leptons?

Answer 12

A:

Particles that interact with the weak nuclear force.

Question 13

Quarks and leptons:

What are baryons?

Answer 13

A:

A hadron made up of 3 quarks

Question 14

Quarks and leptons:

What is a meson?

Answer 14

A:

A hadron made up of a quark and antiquark

Question 15

Quarks and leptons:

What quark causes a particle to be a sigma particle?

Answer 15

A:

A particle with a strange quark.

I.e. uus

Question 16

Quarks and leptons:

What is conserved in interactions?

Answer 16

A:

Mass energy
Charge
Lepton number
Baryon number
Strangeness

Question 17

Quantum phenomena:

What is the threshold frequency?

Answer 17

A:

The minimum frequency of electromagnetic radiation for the metal to emit an electron from its surface.

Question 18

Quantum phenomena:

What is the work function?

Answer 18

A:

The minimum energy needed by an electron to escape from the metal surface

Question 19

Quantum phenomena:

How do you convert from eV to J?

Answer 19

A:

Divide it by

                     1.6 x10^-19

Question 20

Quantum phenomena:

When is wave particle duality observed in the context of light?

What is its wave proof? And it’s particle proof?

Answer 20

A:

Wave like nature is diffraction

Particle like nature is photoelectric effect