Matter and Radiation

Question 1

What is a nucleus made out of?

Answer 1

Protons and neutrons

Question 2

What charge does an electron have?

Answer 2

Negative

Question 3

Define a coulomb

Answer 3

Unit of charge equal to the electrical charge transferred by a steady current of 1 Ampere in 1 second.

Question 4

What is elementary charge?

Answer 4

Electric charge carried by a proton or equivalently the absolute value of the electric charge carried by an electron. e = 1.6 x 10^-19

Question 5

What is an isotope?

Answer 5

An atom with the same number of protons(Atomic number) but a different number of neutrons (mass number)

Question 6

What is each different type of nucleus called?

Answer 6

A nuclide

Question 7

What is specific charge?

Answer 7

Charge of a specific particle divided by its mass

Question 8

Specific charge of a H nucleus?

Answer 8

Charge of +1.60x10^-19 / mass of 1.67x10-27 = 9.58x10^7 CKg^-1

Question 9

Name the 4 fundamental forces

Answer 9

Gravity Electromagnetic force Weak interaction Strong interaction

Question 10

Explain what gravity is

Answer 10

-A force that acts between all particles in the universe. -Has an infinite range -Negligible at an atomic scale -Weakest fundamental force -Mediated by gravitron (undiscovered)

Question 11

What are nucleons?

Answer 11

Protons and neutrons

Question 12

Define pair production

Answer 12

When a particle and it’s corresponding anti-particle are produced from a photon with energy greater than the total rest energy of the two particles

Question 13

Define annihilation

Answer 13

When a particle and it’s corresponding anti-particle collide they annihilate and convert their kinetic energy and rest energies into 2 high energy photons(with energy E=hf)

Question 14

Explain electromagnetic force

Answer 14

-Force that acts between any charged particles. -Repulsive(same charge), attractive (different charge) -Responsible for keeping molecules together -Mediated by virtual photons

Question 15

Explain weak interaction

Answer 15

-Force acts in all particles with 1/2 integer spin (quarks,leptons and baryons but not bosons - elemental bosons and baryons) -This acts over a very short range -Responsible for electromagnetic decay -mediated by W and Z bosons (elemental particles)

Question 16

Explain strong interaction

Answer 16

-Responsible for holding quarks together in hadrons -Binds protons and neutrons inside atomic nucleolus (in these terms it is referred to as the strong nuclear force) -Binding quarks mediated by gluons -Binding protons and neutrons mediated by Pion or Pi Meson

Question 17

Explain the strong nuclear force(residual strong force)

Answer 17

-Over comes the electrostatic repulsion between protons -Keeps nucleus stable -Attractive between 0.5fm-3fm -Repulsive

Question 18

What is alpha decay?

Answer 18

-Release alpha particles (positively charged helium ions) -Reduces mass number of a nucleus by 4 and atomic number by 2

Question 19

What are the two types of beta decay?

Answer 19

Beta +, Beta -

Question 20

What is Beta + decay? (Positron)

Answer 20

-Proton decays into a neutron emitting an electron neutrino and a positron

Question 21

What is Beta - decay?

Answer 21

Neutron decays into a proton emitting an electron and an electron anti-neutrino

Question 22

What is gamma radiation?

Answer 22

-When alpha or beta decay occurs, the nucleus is usually left in an excited state it subsequently releases a high energy photon(gamma particle) to reduce this energy -Photon Y - no mass and no charge

Question 23

Speed of a wave formula

Answer 23

c= f x wavelength

Question 24

Formula for frequency

Answer 24

c/wavelength = f

Question 25

When are photons emitted?

Answer 25

-Fast moving electron stopped -Electron “jumps” from a higher quantum level(shell) in an atom to a lower one

Question 26

Formula for the energy of a photon

Answer 26

E=hf Also can be shown as E = hc/wavelength

Question 27

What does h stand for?

Answer 27

Planck’s constant = 6.63x10^-34

Question 28

What happens when a particle and its corresponding anti-particle collide?

Answer 28

They annihilate and are converted completely into energy(found by E=mc^2)

Question 29

What is called when, a photon spontaneously changes into a particle and it’s anti-particle

Answer 29

Pair production

Question 30

What does an anti-particle have?

Answer 30

-Same rest mass as corresponding particle -Same rest energy as corresponding particle -Opposite charge(if corresponding particle has a charge)

Question 31

How are anti-particles denoted?

Answer 31

Line above the Symbol, apart from the positron which is denoted as e+

Question 32

How can you find the rest energy of a particle?

Answer 32

E= mc^2 m= mass of the particle when stationary c= speed of light

Question 33

How much energy must a photon have for pair production to occur?

Answer 33

At least the rest energy of the two particles that it turns into.

Question 34

How can you work out the energy of photon in pair production?

Answer 34

E= mc^2 (energy of the particle) 2(mc^2) = Energy of the photon

Question 35

Explain the weak nuclear force

Answer 35

-Responsible for Beta decay (both types) -Only occurs with leptons and hadrons, explains why neutrinos are so reluctant to react with anything -Mediators of this force are bosons of which there are 3 types: W+, W- and Z

Question 36

W Bosons

Answer 36

-Non-zero rest mass -Short range; Bosons are relatively massive and consequently are high in energy, so short lifetimes -Can only act over short distances (10^-17m) because of short lifetime

Question 37

Feynman diagrams and

Answer 37

Electron capture on computer