1.1 Matter and Radiation

Question 1

What is the unit for specific charge?

Answer 1

CKg-1

Question 2

Which part of an atom has the highest specific charge?

Answer 2

The electron (high charge/small mass)

Question 3

How does the strong force act on nucleons?

Answer 3

Between 0 and 0.5fm there is strong repulsion, between 0.5 and 3fm there is strong attraction which declines as the particles get further apart

Question 4

What is an alpha particle?

Answer 4

A helium nucleus with 2 protons and 2 neutrons

Question 5

Which nuclei emit alpha radiation?

Answer 5

Mostly heavy nuclei with some smaller neutron deficient nuclei

Question 6

What is the equation for the total energy emitted from a laser?

Answer 6

E= N x hf
hf is the energy of 1 photon
N is the total number of photons emitted

Question 7

What is the equation for the amount of energy transferred per second by a laser and what is it measured in?

Answer 7

E= n x hf, measured in Watts (energy transferred per second)
n is the number of photons transferred per second
hf is the energy of 1 photon

Question 8

What equation links mass and energy?

Answer 8

E=mc(squared)

Question 9

What 3 ways can we create antimatter?

Answer 9

High energy collision experiments
Interactions with cosmic rays
Radioactive decay

Question 10

Name a similarity and difference between matter and antimatter

Answer 10

Both have the same rest mass but have an opposite charge

Question 11

What are the 2 processes to create and destroy matter and antimatter?

Answer 11

Pair production and annihilation

Question 12

Define an electron volt

Answer 12

The energy required to move one electron across a potential difference of one volt

Question 13

How do you convert joules to electron volts?

Answer 13

J/1.602x10-19

Question 14

How do you convert eV to joules?

Answer 14

eV x 1.602x10-19

Question 15

When does pair production occur?

Answer 15

When a high energy gamma ray passes near a nucleus and the gamma ray has enough energy to produce the rest mass of 2 particles

Question 16

What does pair production produce?

Answer 16

A particle and it’s antiparticle

Question 17

What happens to the particles after they have been produced from pair production?

Answer 17

They spiral in opposite directions due to their charge and the nearby nucleus

Question 18

What will happen to positrons produced in pair production soon after their creation?

Answer 18

They will annihilate with another electron and form 2 gamma rays

Question 19

What happens when a particle and it’s antiparticle collide?

Answer 19

The mass of both particles are converted in two gamma rays (to conserve momentum)

Question 20

How would you calculate the minimim frequency of a produced gamma ray from annihilation?

Answer 20

The rest mass of the colliding particle divided by Planck’s constant
E=hf

Question 21

What are the 4 fundamental forces?

Answer 21

Electromagnetic force
Strong force
Weak force
Gravitational force

Question 22

What are the exchange particles of these forces?

Answer 22

Electromagnetic - virtual photon
Weak force - W +/- boson
(Gravitational - graviton)
(Strong force - gluon)

Question 23

What are the differences between the 2 exchange particles we learn?

Answer 23

W +/- bosons: Have a rest mass, limited range, charge

Virtual photon: No rest mass, infinite range, no charge

Question 24

Why is the photon in the electromagnetic interaction ‘virtual’?

Answer 24

Because it travels too short a distance to be seen and never misses the other particle

Question 25

How do you calculate the specific charge of an ion?

Answer 25

The charge of the ion in coulombs divided by the mass of the ion in kg including the protons, neutrons and electrons