Physics Radioactivity Topic- Key Knowledge

Question 1

What is an isotope?

Answer 1

A nucleus with the same number of protons but a different number of neutrons.

Question 2

What is an alpha particle?

Answer 2

• 2 protons and 2 neutrons
• Highly ionising
• Least penetrating (blocked by paper)

Question 3

What is a beta particle?

Answer 3

• A fast moving electron
• Mildly ionising
• Mildly penetrating (Blocked by aluminium sheets)

Question 4

Fuel rods?
What are they made of?

Answer 4

• Where fission happens, Uranium/Throrium

Question 5

Moderator?
What is it made of?

Answer 5

• Slows neutrons to increase probability of reaction happening, water/graphite

Question 6

Control rods?
What are they made of?

Answer 6

*Absorb neutrons to control rate of fission reaction, Boron

Question 7

Shielding?

Answer 7

• Protects environment from irradiation, Lead or concrete

Question 8

What is irradiation?

Answer 8

When a material has been exposed to ionising radiation from the outside but does not become radioactive

Question 9

What is contamination?

Answer 9

When a radioactive isotope has been inserted into a material, causing it to become radioactive

Question 10

What is meant by the half life of a radioactive isotope?

Answer 10

The time taken on average for the number of nuclei to halve

Question 11

Give two medical uses of radiation.

Answer 11

• Medical tracers
• Radiotherapy

Question 12

Give two industrial uses of radiation.

Answer 12

• Thickness gauging
• Leak detecting
• Carbon-dating

Question 13

Give a domestic use of radiation

Answer 13

• Smoke detection

Question 14

What is nuclear fission?

Answer 14

The splitting of a large parent nucleus into two smaller daughter nuclei, releasing energy

Question 15

Why can’t radioactive decay be predicted?

Answer 15

It is a random process

Question 16

What is activity, and what is its unit?

Answer 16

• The number of decays per second in a sample
• Becquerels (Bq)