Phys 4.6

Question 1

Properties of Radioactive Decay

Answer 1

-Spontaneous
-Cannot be controlled
-Unaffected by chemical combination
-Unaffected by physical conditions

Question 2

Alpha Particle

Answer 2

-Helium nuclei consisting of 2 protons and 2 neutrons
- +2 charge
-High ionising power
-Few mm range
-Stopped by paper

Question 3

Beta Particle

Answer 3

-High energy electrons
- -1 charge
-Medium ionising power
-Few m range
-Stopped by aluminium

Question 4

Gamma Rays

Answer 4

-Electromagnetic radiation -After alpha or beta emission, the nucleus emits a gamma ray to leave its excited state and return to a ground state
-Neutral
-Low ionising power
-Many m range
-Stopped by lead

Question 5

Law of Radioactive Decay

Answer 5

The rate of disintegration of a nuclide at any time is directly proportional to the number of unstable nuclei (N) of the nuclide at that time.

Question 6

Decay Constant

Answer 6

The fraction of unstable nuclei that decay each second

Question 7

Half Life

Answer 7

The time for the number of active nuclei at a time to fall to half its value.