Radiation Science Flashcards
Identify the energy transformations that take place within the x Ray tube
Electrical energy within the filament is converted in heat energy and kinetic energy. 99% heat energy and 1% X-ray energy
Explain what is meant by precession in relation to MRI
When spinning protons align themselves with the magnetic field they wobble or precess around the direction of the field applied. The frequency of precession (number of wobbles per second) depends on the strength of the applied magnetic field
State what is meant by the term metastable as applied in radioactivity
Undergoes another decay process. Has excess energy. Turn as metastable and decays emitting gamma radiation to reach ground state
Explain why the primary supply cables to high tension transformers have a large cross-section.
High tension transformers carry a high current. There are relatively large copper wires in the cables. Primary supply has a higher current where as secondary supply has a higher voltage
Using the band theory, distinguish between the electrical conduction properties of insulators and conductors
Draw band diagrams
Insulators have a large forbidden zones. Electrons need a lot of energy to enter conduction band.
Conductors have no forbidden zone
State faradays laws of electromagnetic induction
- A change of the magnetic flux linked with a conductor induced an EMF in the conductor
- The magnitude of the induced EMF is proportional to the rate of change of magnetic flux
Why is tungsten used?
High atomic number
Hugh melting point
Low vaporisation pressure
Two purposes of the nickel cup
Houses the filament
Focuses the electron beam onto the targeted
Explain why ferromagnetic materials exhibit strong magnetic characteristics
Ferromagnetic materials have dipoles arranged in groups called domains. If a magnetic field is applied, the domains will align in the same direction therefore this is a strong magnetic effect. If the magnetic force is removed, the domains will still remain aligned
