Unit 3a Flashcards
Name 2 Materials X-rays are absorbed by
Bone
Metal
What are charged-coupled devices
It is a silicone chip divided into a grid patter to form millions of pixels. They are used to create high resolution pictures.
How do CT scans form images of the body
They use a focused
X-rays to create a 2D image and then rotate the emitter around the body, taking multiple images and piecing them together to make a 3D image
How can X-rays be used to treat cancer
A focused beam of
X-rays can cause cells in the body to ionise
When using X-rays to treat cancer how do doctors minimise the dosage of radiation to the healthy cells.
They can use a led shield to protect some parts of the body
or
Rotate the emitter of X-rays round the cancerous area of the body.
What is ultrasound.
Ultrasound is the use of high frequency sound waves, much higher than the hums hearing range.
Use the equation:
Distance(m)=speed(m/s)*time(s)
to work out:
US travels at 1000m/s the time between the 2 receiving pulses was 0.00004s. How thick is the medium
D=1000*0.00004=0.04
To find the distance from the emitter to the end of the medium the awnser must be devided by 2
0.04/2=0.02m=2cm
Why is US used to monitor a Foetus over X-rays
Because X-rays cause ionising radiation, damaging or killing the child, however US has no knock on effects to the mother or the baby
What is the advantage of a CT scan over US scan
A CT scan can create a high definition image of a object and can even create 3D images. Whereas ultrasound creates 2D fuzzy images
What is refraction.
Refraction is the change in wave direction as it passes from one density medium to another
What are X-Rays
X-rays are High Frequency short wavelength, electromagnetic waves.
What do converging lenses do to incoming light rays
Had a focal point closer to the lens
Magnifies a virtual
Image of an object
What does o diverging lens do to incoming Rays of light
Has a focal point further away form the lens
Makes a virtual image smaller
What 3 things are required when describing the image produced by a diverging lens
It is a virtual image which is the right way up, smaller and is on they same side of the lens as the object no matter where it is
What 3 things are required when describing the image produced by a converging lens
It is a virtual image which is the right way up, smaller and is on they same side of the lens as the object no matter where it is
