Nuclear Physics

Question 1

Nuclear fusion

Answer 1

• The process by which light nuclei (e.g. Hydrogen nuclei) can join together to form heavier nuclei
• with the release of energy

Question 2

Nuclear fission

Answer 2

• The process by which heavy nuclei (e.g. Uranium nuclei) can split apart to form a lighter daughter nucleus
• with the release of energy

Question 3

In order to fuse two light nuclei, work must be done against… (name the force)

Answer 3

the electric force

due to the electrostatic repulsion of the two positive nuclei

Question 4

When two light nuclei fuse, work is done by… (name the force)

Answer 4

the strong nuclear force

Question 5

When two light nuclei fuse, is the mass of the new nucleus more, less or the same as the total mass of the original nuclei?

Answer 5

Less!

Question 6

A Uranium nucleus undergoes fission, forming two daughter nuclei and releasing 3 neutrons. Is the total mass of these products more, less or the same as the mass of the orginal nucleus?

Answer 6

Less!

Question 7

The binding energy of a nucleus

Answer 7

The minimum energy needed to separate a nucleus into its constituent nucleons

Question 8

Name the element whose nucleus has the highest binding energy per nucleon

Answer 8

Iron

Question 9

Name the element with the most stable nucleus

Answer 9

Iron

since the binding energy per nucleon is greater for iron than for any other element

Question 10

‘Induced’ nuclear fission occurs when what particle strikes a large, unstable nucleus?

Answer 10

A neutron

Question 11

Name the products of ‘induced’ nuclear fission

Answer 11

• smaller daughter nuclei
• 3 or more neutrons
• energy (in the form of the K.E. of the products)

Question 12

In a nuclear power station, what is a ‘fuel rod’?

Answer 12

Fuel rods contain the nuclear fuel.

Question 13

Give two examples of nuclear fuels that might be used in a fuel rod.

Answer 13

Uranium, Plutonium.

Question 14

In a nuclear power station, what is a ‘moderator’?

Answer 14

A moderator is a material used to slow down the neutrons (released by fission reactions)
so that they are more effective at causing fission

Question 15

Give an example of a material that might be used as a moderator.

Answer 15

Graphite, heavy water

Question 16

Why must the nuclei released by fission reactions need to be slowed down?

Answer 16

Slower neutrons are more effective at inducing nuclear fission

Question 17

In a nuclear power station, what is a ‘control rod’?

Answer 17

A rod that absorbs neutrons, that can be raised and lowered between the fuel rods to control the rate of the fission reaction.

Question 18

Give an example of a material that might be used to make a control rod.

Answer 18

Boron