Radioactivity

Question 1

What is a:

a) Alpha particle? (α)
b) Beta particle? (β)
c) Gamma wave? (γ)

Answer 1

a) A high energy helium nucleus
b) A high energy electron
c) A photon of energy/high frequency EM wave

Question 2

What are the three methods of identifying radiation types?

Answer 2

› Penetration
› Using an electric field
› Using a magnetic field

Question 3

When using penetration to identify radiation types, what stops each type of radiation?

Answer 3

› Alpha radiation is stopped by paper
› Beta radiation is stopped by aluminium
› Gamma waves are mostly stopped by lead or concrete

Question 4

What should also be measured when using penetration to identify radiation types?

Answer 4

› Background radiation should be measured before placing any source of absorber
› The initial activity of the source should be measured with no absorber

Question 5

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

Answer 5

The time taken for the number of radioactive nuclei or activity to fall to half its initial value

Question 6

What is meant by the activity of a radioactive substance? And what is activity measured in?

Answer 6

› The rate of decay / the number of disintegrations per second
› Measured in Bequerels (Bq)