NUCLEAR PHYSICS

Question 1

Nucleons

Answer 1

Protons and Neutrons

Question 2

Mass defect

Answer 2

The difference between total mass of constituent nucleons and mass of nucleus

Question 3

Binding energy

Answer 3

The energy released when a nucleus is formed from its constituent nucleons OR the energy required to separate a nucleus into its constituent nucleons.

Question 4

Binding energy per nucleon

Answer 4

The energy released per nucleon when a nucleus is formed from its constituent nucleons.

Question 5

When will radioactive decay happen?

Answer 5

When the binding energy per nucleon of the products is higher than the binding energy of the reactants, so energy is released and the products are more stable.

Question 6

Why do fusion and fission both release energy?

Answer 6

The binding energy per nucleon of the products in each case is higher than the binding energy per nucleon of the initial nuclei. Iron has the highest binding energy per nucleon, so splitting apart nuclei heavier than this releases energy and fusing nuclei lighter than this releases energy.

Question 7

Beta minus particle

Answer 7

Fast moving electron

Question 8

Beta plus particle

Answer 8

Fast moving positron

Question 9

Alpha particle

Answer 9

Helium nucleus (2 protons and 2 neutrons)

Question 10

Gamma ray

Answer 10

A photon of electromagnetic radiation of very high energy that is emitted in the decay of certain radioactive nuclei and in electron-positron annihilation.

Question 11

Background radiation

Answer 11

Low levels of radiation in the environment.

Question 12

Activity

Answer 12

The activity, A, of a radioactive sample is the number of nuclei decaying every second.

Question 13

Count rate

Answer 13

The number of ionising particles detected per second.

Question 14

Becquerel

Answer 14

The unit of radioactive decay, 1 Becquerel is equivalent to one decay per second.

Question 15

Ionising radiation

Answer 15

It is radiation that has enough energy to remove tightly bound electrons from the orbit of an atom during an interaction, causing the atom to become charged or ionised.

Question 16

Unstable atoms

Answer 16

When the binding energy per nucleon is not high enough to hold the nucleus together, unstable atoms will lose neutrons and protons as they attempt to become stable.

Question 17

Spontaneous decay

Answer 17

The idea that radioactive decay happens on its own without any outside influence (eg. temperature) to get the isotope to decay.

Question 18

Random decay

Answer 18

The idea that one cannot know or predict precisely when the next decay will happen or which nucleus will decay. The radioactive atom will have a fixed probability of decaying in a given time interval.

Question 19

Geiger

Answer 19

Muller tube: An instrument used for measuring ionising radiation.

Question 20

Photon

Answer 20

A discrete packet of electromagnetic radiation energy which contains a particular amount of energy that depends on the frequency of that radiation.

Question 21

Isotope

Answer 21

Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei.

Question 22

Neutrino

Answer 22

A neutral subatomic particle that is emitted from beta – decay and interacts only through the weak interaction.

Question 23

Decay constant

Answer 23

It is a measure of how quickly an isotope will decay: the bigger the value of the constant, the faster the rate of decay.