Topic 4 - Motion of Particles Flashcards
What is a cyclotron
particle accelerator
what happens to the velocity when something is moving in a circular motion
velocity is constantly changing.
velocity is both the speed and the direction of an object and in a circle the direction is constantly chaining, which means the object is accelerating.
this means there is a resultant force acting upon it.
what is centripetal force
the force that acts towards the centre of the circle that keeps something moving in a circle.
What effect does a magnetic field have on a charged particle
a charged particle in a magnetic field will experience a force. the force on a moving charge is always perpendicular to its direction of travel making the particle follow a curved track.
What does the direction of force on a particle in a magnetic field depend on
the particles charge, positive and negative particles curve in opposite directions
What shape is the movement of a charged particle in a magnetic field
spiral because the particles lose energy and slow down as they interact with other particles. The less energy they have the more curved their path will be.
How do cyclotrons work?
Charged particle starts in centre of two electrodes called dees.
they accelerate ion across gap because of alternating potential difference
the ion is attracted from one side to the other due to opposite charge and gains energy (accelerate)
Strong magnetic field to create circular motion
As the protons travel faster, their radius around the dees increases until finally they are ejected as a high speed proton beam
What is proton enrichment?
creating a radioactive isotope by bombarding an element with protons. They are absorbed by the nucleus which increases the proton number so you get a new element.
A proton needs a lot of energy to be absorbed into the nucleus so the process must take place in a cyclotron. the radioisotopes are usually positron emitters which are useful in hospitals for PET scans.
What are three examples of useful radioisotopes
fluorine-18 made from oxygen-18 and has a short half life.
Carbon-11 made from nitrogen-14 and has a half life of 20 min
Nitrogen-13 made from oxygen-16 and has a half life of 10min
what is another use of particle accelerators other than medical purposes
used to find out about the universe and what its made of
How do scientists use particle accelerators to find out more about the universe
they smash particles together at high speeds to see what happens - what kind of radiation is given off, what new particles are created, etc. this gives clues about how the universe works.
Why is research done internationally?
not every country can afford its own particle accelerator and its useful to combine the expertise of lots pf specialists. E.g the Large Hadron Collider at Geneva, Switzerland.
What was the Large Hadron Collider designed to find out
largest and most powerful ever built.
designed to recreate conditions just after big bang by colliding two beams of protons head on a mega fast speeds
what does conservation of momentum mean
the total momentum before is equal to the total momentum after (so long as there aren’t any external forces acting)
What is an elastic collision
one where momentum and kinetic energy is conserved - no energy is dissipated as heat, sound etc.
