WorksheetsA Level Radioactive Decay Basics
Total questions: 11
Worksheet time: 6mins
When measuring the count rate from a radioactive source it is usual to also measure the background count rate.
The background count rate must be
as large as possible for an accurate experiment.
measured when the source is in place.
recorded for the same time as the count rate.
subtracted from the count rate measured from the source.
Before carrying out an experiment to measure the activity from a radioactive source, it is usual to measure the background count. The background count obtained is not affected by the
location of the experiment.
temperature of the surroundings.
time interval used for the count.
type of detector being used.
The ionising properties of radiations determine their penetrating power.
Which of the following statements is correct?
α-particles are not very ionising so they are stopped by thin paper.
α-particles are very ionising so can only travel a few centimetres in air
γ-radiation is very penetrating because it is very ionising
γ-radiation is not very penetrating because it is very ionising
Radioactive decay is a spontaneous process.
This means that we cannot
influence how a nucleus will decay.
influence when a nucleus will decay.
know how much energy is emitted.
know what radiation will be emitted.
α, β and γ radiation are all able to penetrate matter.
Select which correctly identifies the penetration and ionising ability of γ radiation.
High penetration, High ionising ability
Low penetration, high ionising ability
High penetration, low ionising ability
Low pentation, low ionising ability
A radioactive source is placed a few cm away from a detector. There is no change in the count rate when a thin aluminium foil is placed between the source and the detector, but the count rate is reduced to the background rate when a 0.5 cm aluminium plate is introduced.
These observations show that the source must be emitting
alpha and beta radiation.
beta and gamma radiation.
beta radiation only.
gamma radiation only.
A radioactive source is placed 2 cm from a detector. The count rate decreases slightly if a sheet of paper is placed between the source and the detector. It is reduced to background radiation level when the paper is replaced with a 1 cm thickness of aluminium.
The correct conclusion is that the source emits
alpha radiation only.
alpha and beta radiation.
beta and gamma radiation.
gamma radiation only.
In a famous thought experiment, Schrödinger imagined that a cat is locked in a box, along with a radioactive atom that is connected to a tube containing a deadly poison. If the atom decays, it causes the tube to smash and the cat to die.
The random nature of radioactive decay means that the radioactive atom will
decay after one half-life.
probably decay after one half-life.
have a fixed probability of decaying in a given time interval.
have a number of possible decay paths.
Radioactive decay is said to be a spontaneous process.
This means that
we cannot know when a nucleus will decay.
we cannot know which nucleus will decay next.
we cannot know how many nuclei will decay.
we cannot influence when a nucleus will decay.
In an experiment to measure the activity of a radioactive source the measured activity should always be corrected by
adding the background count.
adding the background count rate.
subtracting the background count.
subtracting the background count rate.
Nuclear particles and nuclear radiation may cause ionisation as they pass through matter.
Which of the following is the most ionising?
α particles
β particles
γ rays
neutrons
