9. Radioactivity Flashcards
During alpha scattering how many particles are deflected at less than 90 degrees?
Around 1 in 2,000.
During alpha scattering how many particles are deflected at more than 90 degrees?
Around 1 in 10,000.
What apparatus are used in the alpha scattering experiment?
A microscope with a florescent screen, an alpha source, and a sheet of thin metal foil. All are in an evacuated metal container.
What does alpha scattering show us?
Most of an atom’s mass is concentrated in the nucleus, the nucleus is positively charged, and the nucleus is around 10,000 times smaller than the atom as a whole.
If an alpha particle collides head-on with the nucleus, at what angle does it deflect and why?
180 degrees because the electrostatic force of repulsion increases with decreased separation between the nucleus and the alpha particle.
The closer an alpha particle is to a head-on collision with the nucleus, the ________ the least distance approach?
Smaller.
During alpha scattering experiments, why must the foil be as close to one atom thick as possible?
To prevent particles being scattered more than once.
Which type of radiation is the most ionising?
Alpha.
Which type of radiation is the most penetrating?
Gamma.
What are the three greatest contributors to background radiation?
Air (e.g. radon gas), medical sources, and ground & buildings.
Why are film badges used?
They are used by anyone using equipment that produces ionising radiation to monitor their exposure to the radiation. When developed the more black the film, the more exposed they have been to the radiation.
Why is ionising radiation dangerous?
It damages living cells.
What is a somatic effect?
An effect on health to the person being directly affected by radiation.
What is genetic effect?
An effect on the health of future generations.
What are uses of alpha, beta, and gamma radiation?
Alpha - Smoke alarms .Beta - To treat certain cancers. Gamma - Radioactive tracers in blood or PET scanners.
