Nuclear + Particle Physics (11) (23)

Question 1

“Nuclear decay is random and spontaneous”

Describe what is meant by random and spontaneous decay

Answer 1

• Random: One cannot predict which nuclei will decay or when they will decay. One cannot determine a rate of decay absolutely; only a probability.
• Spontaneous: Nuclear decay occurs without interference from external factors. It cannot be sped up or slowed down by heating, for example.

Question 2

What is radioactive decay? [3]

Answer 2

• When an unstable nucleus has a spontaneous emission of particles which are ionising.

Question 3

Define half-life of a nucleus

Answer 3

• The mean time taken for half the active nuclei in a sample to decay.

Question 4

Define the decay constant

Answer 4

• The probability that an individual nucleus will decay per unit time.

Question 5

Define the activity of a nucleus

Answer 5

• The rate of decay of nuclei
• A = (dN)/(dt)