PHYSICS Flashcards
What did Rutherford discover
Positive nucleus surrounded by negative electrons in shells
How did Rutherford discover the plum pudding model
by firing alpha particles at gold foil
How can electrons jump to higher energy levels
absorption of electromagnetic radiation
What are alpha particles made from
a helium neuclei with 2 protons and neutrons
characteristics of alpha radiation
Highly ionising low penetration stopped by paper
How does an alpha particle equation work
atomic mass decreases by 4 and atomic number decreases by 2
What is beta radiation made form
electron emitted from the nucleus
what are the characteristics of beta radiation?
Mid ionising ability mid penetration stop by aluminium
How do beta equations work?
Atomic mass no change atomic number increased by one
what are gamma waves made of?
EMS waves
what are the characteristics of gamma radiation?
Low ability high penetration stop by several inches of lead
what level is background radiation?
low
What is contamination?
Contamination is the unwanted presence of materials containing radioactive atoms on other materials
what is irradiation ?
Radiation is the process of exposing an object to nuclear radiation. It does not cause the object to become radioactive.
what is half life?
Half life is the amount of time it takes the number of radioactive nuclei on of the isotope to Halle
What does the number of atoms and count rate do
every half life?
half
What is the half-life of carbon 14 used for?
age living things
why is radiation harmful?
Ionising
what can radiation do in humans?
Can cause mutations to DNA leading to cancer or kill the cell
what type of radiation does smoke detectors use?
Alpha
What type of radiation is thickness monitors use?
beta
How do medical use radiation?
Can be used to explore internal organs and control or destroy unwanted tissues
what can gamma radiation used to do?
kill cancer cells
which types of radiation can be used as a tracer? The half-life must be long enough to detect but not too long.
beta or gamma
Natural sources of background relations include cosmic rays food and drink rocks and buildings all contribute how much percentage of background radiation?
12.5% each
radon gas contributes to what percentage of radiation
50%
Man made sources of radiation come from nuclear fallout from weapon test nuclear disasters and medical use how much do they contribute to background radiation?
12.5%
What is Fission
Vision is a splitting of an atomic nucleus into two smaller nuclei and two more neutrons releasing energy
in nuclear power stations, vision is induced in what two elements by firing a neutron at it
Uranium 235
plutonium 239
what does fission cause
fission is a chain reaction and causes more nuclei to split
Why is nuclear waste hard to dispose of?
radioactive
Nuclear fallout from a power station can do what?
Make an area uninhabitable
what is fusion?
Fusion causes two atoms to combine, releasing vast amounts of energy
when does fusion happen?
Happens naturally in a star when hydrogen fuses to form helium
how can this be attempted on earth
At very high temperatures 7,000,000° (7million degrees)
