P4 Radiation For Life Flashcards
How can electric shocks be avoided
If the object that is likely to become charged is connected to the earth through an earth wire
In a factory where machinery is at risk of becoming charged then the operator will stand on an insulating rubber mat
What 2 things use static electricity to work
Dust precipitator, defibrillators and paint spraying
How does a dust precipitator work
As the dust particles go up the chimney they are attracted to to the metal plate due to the metal plate having the opposite charge to the dust particles
How does paint spraying work
The spray gun is charged, this gives all the paint particles the same charge, therefore these charges repel away from each other due to the fact that like charges repel, giving out a fine,even spray, the object is given the opposite charge to the paint so the paint is attracted to the obj ft and little paint is wasted
How do defibrillators work
Two paddles are charged to a high voltage and placed frilly on the patients heart to ensure good electrical contact, then an el citric charge is passed through the the patient to make the heart contract
What does the live wire, neutral wire and earth wire do
Live wire - carries voltage around the house
Neutral wire - completes the circuit providing a return path for the current
Earth wire - connected to the case of the appliance to prevent it becoming live, it stops a person receiving an electric shock as it makes the current flow back to the ground
What are compressions in a wave and what are rarefactions
Regions of higher pressure and rarefactions are regions of lower pressure
What are the features of longitudinal sound wave
Can’t travel through a vacuum, denser the medium the faster it travels, higher frequency smaller wavelength, louder the sound the higher the amplitude
What is the difference between longitudinal waves and transverse waves
Longitudinal waves have vibrations of particles which go in parallel to the direction of the wave, transverse waves have vibrations of particles which go at right angles to the direction of the wave
How is ultrasound used to break down kidney bones
High powered ultrasound is directed at the kidney stones and force them to vibrate extremely vigorously causing them to break into tiny pieces which can be excreted through urine
How is ultrasound used in body scans
At each boundary between different tissues, some ultrasound is reflected back, the returning echoes come back at different times which builds up the image of the internal structure
Why is ultrasound preferred to x-Rays
It is able to produce images of soft tissue and it doesn’t damage living cells
What is the half life of a radioisotope
The average time for half the nuclei present to decay
Why are alpha particles very good ionisers
Because they are the largest particles emitted in decay. This means that they a re more likely to strike atones of the material they are passing through, ionising them
Where does most background radiations come form
Natural sources such as food, rocks like granite, cosmic rays from space and radioactivity naturally in the air
How is gamma used to trace a blockage in a pipe and why
Game is used because it can penetrate the surface so it can be detected form the surface, and it is used by putting it into a pipe, a detector is passed along the ground above the path of the pipe, an increase in activity is detected at the leak and then there I little or no activity after this point
How do smoke alarms work
The smoke detector releases alpha particles which ionise the air creating a tiny current that can be detected, smoke partially blocks this, so there is less ionisation of the air which the smoke detector picks up
How can you date radioactive material such as uranium
The uranium isotopes in the rocks go through a series of decay and eventually forms a stable isotope of lead, by comparing the amount of lead and uranium present in a rock sample you can find an approximation of its age
How does carbon dating work
All living the NGOs have carbon-14 present in it, when it dies carbon-14 stops being produced and decays, so the ratio of carbon-14 in the object shows how old it is
How do x-rays work
High-speed electrons are fires at metal targets
How can radioactivity be used as a tracer inside s patients body
Gamma radiation is put in the patients body through food , drink or injection, then it’s progress through the next Indy can be seen through a detector such as a gamma camera
How are radioisotopes used to destroy a tumour in the body
Three sources of radiation are placed evenly around with the Timor being placed in the centre, and such of these give a third of the dosage, therefore healthy tissue only receives a third of the dose. The radiation should the destroy the tumour
How does nuclear fission work in nuclear power stations
A neutron is absorbed by the nucleus of uranium-235 making it less stable so it splits and releases 3 neutrons, these neutrons then hit other uranium molecules and a chain reaction occurs
How can nuclear fission be controlled
Firstly born control rods can be raised or lowered, then the boron absorbs the neutrons so fewer neutrons are available to split more uranium nuclei.
Also graphite moderators slow down the fast moving neutrons slowing down the process
Revise fusion
Pg.38
What happens to a polythene rod when it is rubbed with a duster
Electrons are transferred from the duster to the polythene rod, making the polythene rod negatively charged
