NAT 5 -Radiation

Question 1

What are the 3 types of Nuclear Radiation?

Answer 1

-Alpha
-Beta
-Gamma

Question 2

What is Alpha?

Answer 2

-A helium Nucleus
-2 Protons + 2 Neutrons
-Has a Charge of +2
-Strongly Ionising (causes nearby neutral atoms to lose electrons + become charged)
-Weakly penetrating

Question 3

What is Alpha blocked by?

Answer 3

Blocked/absorbed by a few cm of air or a sheet of paper

Question 4

What is Beta?

Answer 4

-A fast moving high energy electron
-Has a charge of -1
-Weakly Ionising

Question 5

What is Beta blocked by?

Answer 5

Blocked/absorbed by a few mm of aluminium

Question 6

What is Gamma?

Answer 6

-A high frequency, high energy electromagnetic wave
-Neutral/no charge
-Weakly Ionising

Question 7

What is Gamma blocked by?

Answer 7

Blocked/absorbed by several cm of Lead or several m of Concrete

Question 8

What is a Activity?

Answer 8

-The Activity of a source tells us how many nuclei decay (Emit Radiation) per second

-Activity is measured in units called Becquerels (Bq)

Question 9

What is the Activity Formula?

Answer 9

. Number of Decays
Activity = ——————————–
Time in Seconds

														OR
														        N 
														A = -----
														        t

Question 10

What is a Half-Life of a source?

Answer 10

The half-life of a source is:
1.The time taken for the activity to drop to half of its original value
2.The time taken for half the nuclei in the sample to decay

Question 11

What is Absorbed Dose?

Answer 11

Absorbed dose is the number of joules of energy absorbed per kg of mass.
Energy
Absorbed Dose = ————
Mass