Nuclear

Question 1

What three findings led to the standard model through Rutherford’s experiment?

Answer 1

Most a particles travelled through gold foil with little deflection (EMPTY SPACE)

a particles deflected away from nucleus, repulsive force necessary (NUCLEUS CHARGED)

Question 2

Why is radioactive decay described as a random and spontaneous event?

Answer 2

RANDOM: (1) Cannot predict when a particular nucleus will decay (2) Each nucleus within sample has the same chance of decay per unit time.

SPONTANEOUS: (1) Not affected by presence of other nuclei in the sample (2) External factors i.e. pressure

Question 3

Fundamental Particle

Answer 3

No internal structure & cannot be split into smaller particles

Question 4

Ionising Radiation

Answer 4

Radiation removes electrons from atom leaving it positively charged

Question 5

Radioactivity

Answer 5

Process by which unstable nuclei emit ionising radiation

Question 6

Activity

Answer 6

Rate at which nuclei decay (Bequerels)

Question 7

Annihalation

Answer 7

Process by which a particle and its antiparticle interact and their combined mass is converted to energy via E=MC^2

Question 8

Binding Energy

Answer 8

Minimum energy required to completely separate a nucleus into its constituent protons and neutrons

Question 9

Thermal Neutrons

Answer 9

Neutron in fission reactor wuth mean KE similar to the Thermal energy of particles in the reactor core - slow neutrons

Question 10

Induced fission

Answer 10

Nuclear fission occurring when a nucleus becomes unstable on absorbing another particle (i.e. neutron)

Question 11

Chain reaction

Answer 11

Reaction where neutrons from an earlier fission stage are responsible for further fission reactions leading to an exponential growth in the rate of reactions

Question 12

Moderator

Answer 12

Substance used to slow down the fast neutrons produced in fission reactions so they can propagate the fission reaction

Question 13

With what forces do Quarks and Leptons intra-act?

Answer 13

Quarks = Strong Nuclear force

Lepton= Weak Nuclear Force

Question 14

Why are gamma photons emitted?

Answer 14

When nucleus dropping to its ground state following the emission of an a or b particle.

Question 15

Measuring intensity of gamma radiation from source with a count rate may not be reliable, why?

Answer 15

• Gamma rays emitted in all directions so the detector only records those emitted in one direction.
• The efficiency of the detector is not 100%, the detector only records a fraction of the gamma rays that pass through it.
• The body of the sample itself may absorb some of the gamma rays inside of it.

Question 16

Describe what happens when a proton and antiproton meet, in terms if the photons (slow-moving)

Answer 16

Two Y-photons released with equal energy and travelling in opposite directions