Radiation Flashcards
Explain why this γ-emission does not affect the numbers in the equation.
has no charge
Suggest one reason why a nucleus of thallium-208 is unstable.
excess neutrons
How to calculate neutrons.
Top-Bottom=Neutrons
How to calculate electrons.
Same as protons in a neutral atom
From the data given for positions A, B and C, deduce the type of emissions coming from the radioactive source. Explain your reasoning.
B- gamma, not deflected, not charged
C- beta, charged particles deflected (L rule)
A- background detected here
State the nature of γ-rays
electromagnetic radiation of high frequency and short wavelength
Compare the deflections of the paths of the two types of particle.
deflect in opp directions
β deflected more
Describe the path of the beta particles.
curved path
deflected towards positively charged plate
State the nature of an α-particle.
2 protons, 2 neutrons
Describe how an electric field between two charged plates could be used to determine whether a beam of particles consists of α- or β-particles.
α towards negative (plate)
β towards positive (plate)
State what is meant by the term isotopes
Different version of the same element.
Same number of protons.
Different number of neutrons (,,a diff nucleon number)
State and explain the type of radiation that must be emitted by the isotope for the leak to be detected.
Gamma, can penetrate through the surface and ground and reach the detector unlike the other radiation which are stopped before that
The half-life of the isotope used is 6.0 hours.
Explain why an isotope with this half-life is suitable for a crack in a water pipe.
long enough to find leak
short enough to disappear quickly
What is alpha stopped by?
thin sheet of paper
What is beta stopped by?
thin sheet of aluminium
What is gamma stopped by?
thick lead or concrete
What is the alpha charge?
+ 3.2 × 10–19
What is the beta charge?
-1.6 x 10 -19
The radiation is said to be ionising. Explain what this means
atoms lose electrons
α-particles are more strongly ionising and have a shorter range in air than γ-rays.
Use your knowledge of the nature of these radiations to explain these differences.
(2 points)
α travels more slowly, loses energy with each collision so range is short
α is charged, somore ionising because it has greater charge
At first, the detector continues to register a low count rate sometimes slightly less than the count rate registered without the source.
The count rate suddenly increases to a very high value when the source is very close to the detector.
Explain these changes in the count rate.
Low count rate due to background.
Slightly less due to random decaying fashion.
High due to emission from source.
He notices that the count rate registered by the detector every year is slightly smaller than it was the previous year.
Suggest why this is so.
Decay of source slowed down =
Activity decreased due to less radioctive nuclei
A lead sheet of thickness 10 mm is positioned between the detector and the radioactive source.
State and explain what happens to the count rate on the detector.
decreases, not completely absorbed
Suggest why the paths of the particles in the magnetic field are curved.
the force on the particles is perpendicular to their paths