5.2- Radioactive

Question 1

Where does radioactivity come from? [2]

Answer 1

1. Unstable radioactive isotopes (when they undergo decay)
2. they spit out high energy particles

Question 2

Explain background radiation [2]

Answer 2

1. Small amount of radiation around us at all times
2. comes from many sources- naturally occuring unstable isotopes

Question 3

What are the sources of background radiation? [5]

Answer 3

1. radon gas (in the air)
2. rocks and buildings
3. food and drinks
4. cosmic rays
5. medical rays

Question 4

How does background radiation change in high altitudes

Answer 4

increases because of more exposure to cosmic rays

Question 5

How does background radiation change in underground mines

Answer 5

Increases because of all the rocks around

Question 6

How does a Geiger-Muller tube work [3]

Answer 6

The tubes transmit an electric pulse everytime radiation is absorbed producing a clicking sound.
- the radioactive particle ionises the gas inside which triggers a click
- signal is also sent to a counter that counts how many clicks there are

Question 7

Describe Alpha radiation [3]

Answer 7

1. a helium nucleus- 2 protons, two neutrons
2. highly ionising
3. weakly penetrating (blocked by 5 cm of air)

Question 8

Describe Beta radiation [3]

Answer 8

1. an electron
2. medium ionising effect
3. medium penetration (blocked by 50 cm of air/sheet of metal)

Question 9

Describe gamma radiation [3]

Answer 9

1. electromagnetic waves
2. weak ionising effect
3. highly penetrating

Question 10

Define half life

Answer 10

Half life is the time taken for the number of radioactive nuclei to halve, or the time taken for the count rate/activity to halve

Question 11

Practical radioactive materials

Answer 11

Radiotherapy, Smoke alarms