Extension Flashcards
What is an X ray
A high energy em wave that gets absorbed by dense materials
What are ultrasound scans used for
Breaking kidney stones
Pre-natal scanning
Measuring speed of blood flow
What is radiation
Energy from a source
What affects intensity of radiation
Distance and what it passes through
What is refraction
A change in direction and speed
What do converging lenses do
Make parallel rays bend towards the focal point
What type of image does a diverging lens make
Virtual
How do your correct short sight
Diverging lenses
How do you correct long sight
Converging lens
What is smells law
N = sin(angle of incidence) / sin(angle of refraction)
What is total internal reflection
Angle of incidence is greater than the critical angle all light is internally reflected
In optical fibres why must it be narrow
To keep angles above critical angle
Equation of kinetic energy
Electronic charge x accelerating potential difference
Why are x rays dangerous
Ionise loving cells
What is the inverse square relationship
If you move twice as far from the source it is spread 4 times the area
What is a fluoroscope
A device that uses X rays and a fluorescent screen to obtain moving pictures of the inside of the body
What happens when the heart beats
An action potential passes through the atria making them contact, soon after another passes through the ventricles making them contract
What records action potentials
Electrocardiograph
Equation for heart rate
Frequency (Hz) = 1 / time period
What does a pacemaker do
Keeps the heart beating steadily using small electrical impulses to stimulate the heart beat
What does a pulse oximetry do
Measures the amount of oxygen carried by haemoglobin in the blood
How does a pulse oximeter
Has a transmitter which emits two beams of red light and a photo detected to measure light
As the beams pass through some of the light is absorbed by the blood reducing the amount of light seen by the detector
What is alpha
Helium nucleus
Slow and heavy
Strongly ionising
What is beta
An electron
Light and fast
Moderately ionising
What is gamma
Em radiation
No mass
Weak
What will make a nucleus unstable
Too many neutrons
Too few neutrons
Too much energy
What is unstable about a nucleus above the curve
Too many neutrons
What happens when there are too many neutrons
Beta minus decay
Protons number increase by one
What happens when there are to few neutrons
Beta plus decay
Protons number decreases by one
What happens when there is too much energy in a nucleus
Gamma radiation emitted
Charge of an up quark
2/3
Relative mass of an up quark
1/3
Relative charge of a down quark
-1/3
Relative mass of a down quark
1/3
What makes a good tracer
Beta and gamma
Short half life
How do PET scans diagnose illness
Given glucose with a positron emitting isotope
Where there is a cancer cell the glucose is used faster causing annihilation which is seen by the scanner
What is internal radiation therapy
Radioactive material is placed near the tumour which gives a high dose to a small part of the body
How does external radiation therapy work
Gamma rays carefully focused at the tumour but damage can be done to healthy cells but has many side effects
