Nuclear physics Flashcards
What did Rutherford scattering demonstrate?
Rutherford scattering demonstrated the existence of a nucleus.
What was the Plum Pudding Model, and why was it replaced?
The Plum Pudding Model proposed that an atom had a sphere of positive charge with evenly distributed negative charges. Rutherford scattering disproved this model, leading to the adoption of the Nuclear Model, which posits a small, dense, positively charged nucleus.
Describe Rutherford’s apparatus in the alpha source and gold foil experiment.
Rutherford’s apparatus included an alpha source, a gold foil in an evacuated chamber covered in a fluorescent coating, and a microscope to observe the path of alpha particles.
According to the Plum Pudding Model, what were the expected results in the alpha source and gold foil experiment?
According to the Plum Pudding Model, positively charged alpha particles were expected to be deflected by a very small amount when passing through the foil.
What were the observed results in Rutherford’s experiment, and what did they suggest?
Most alpha particles passed straight through the foil with no deflection, suggesting that the atom is mostly empty space.
A small amount of particles were deflected by a large angle, suggesting that the centre of the atom is positively charged.
Very few particles were deflected back by more than 90°, suggesting that the centre of the atom is very dense and small.
What conclusions were drawn from Rutherford’s experiment?
The conclusions were that the atom has a small, dense, positively charged nucleus at its centre.
How can different types of radiation be identified using a simple experiment?
Measure background count with a Geiger-Muller tube.
Place the radiation source close to the tube and measure count rate.
Introduce a sheet of paper - significant count rate decrease indicates alpha radiation.
Repeat with aluminum foil (significant decrease suggests beta radiation) and lead block (significant decrease indicates gamma radiation).
How are alpha, beta, and gamma radiation used in monitoring material thickness during production?
Beta radiation in the production of materials like aluminum foil.
Alpha radiation for the production of paper.
Gamma radiation for steel sheet production.
What are the uses of gamma radiation in medicine?
As a detector: Short-lived radioactive sources emitting gamma radiation help diagnose patients using gamma cameras.
Sterilizing surgical equipment: Gamma radiation kills bacteria on equipment.
In radiation therapy: Gamma radiation targets and kills cancerous cells but can also harm healthy cells.
Describe the relationship between intensity, distance, and gamma radiation according to the inverse square law.
The intensity of gamma radiation (I) follows an inverse square law
(I = xk^2), where x is the distance from the source.
Why is alpha radiation considered highly ionizing and dangerous?
Alpha radiation is highly ionizing and dangerous if inhaled or ingested as it can ionize body tissue.
What safety measures should be followed when handling radioactive sources?
Use of long-handled tongs.
Store in a lead-lined container when not in use.
Keep the source as far away as possible from oneself and others.
Never point the source towards others.
Why is it important to measure background radiation when taking readings of a radioactive source?
Background radiation is constant and must be measured first; subtracting it from the total count rate gives the corrected count, which represents the actual count rate caused by the source.
