P7.4 More about alpha, beta, and gamma radiation Flashcards
What does an alpha particle get stopped by?
A thin sheet of paper
What does a beta particle get stopped by?
Aluminium sheet
What does a gamma ray get stopped by?
Thick lead sheet
What is ionisation?
The radiation from a radioactive substance can knock electrons out of atoms
What is irradiated?
When an object is exposed to ionising radiation it is said to be irradiated
What is radioactive contamination?
Is the unwanted presence of materials containing radioactive atoms on other materials - hazard from contamination is due to the decay of the nuclei
Why is alpha radiation more dangerous in the body?
Because the ionising power of alpha radiation is much greater than the ionising power of beta or gamma radiation
How can you reduce the exposure of ionising radiation ?
Keep as far as possible from the source of radiation
Spending as little time as possible in at-risk areas
Shielding themselves by staying behind thick concrete barriers
How do smoke alarms work?
They contain a radioactive isotope that sends out alpha particles into a gap in a circuit in the alarm
Alpha particles ionize the air in the gap so there is a current across the gap
Smoke absorbs the alpha particles preventing them from ionizing the air - so current across the gas drops and alarms sounds
Why cant beta or gamma particles be used in smoke detectors?
They do not create enough ions to make the air in the gap conduct electricity
How does automatic thickness monitoring work?
Uses a radioactive source that sends out B radiation - amount of radiation passing through the oil depends on the thickness of the foil
Detector measures the amount of radiation passing through the foil - if foil too thick detector reading drops and sends a signal to increase the pressure of the rollers on the metal sheet
