Medical applications of physics AQA P3.1

• Wave length is the same as the diameter of an atom
• Cause ionistation which can cause cancer
• Used to destroy tumors at skin surface
• Absorbed by metal and bone
• High energy electromagnetic wave

• Tube rotates so image is taken in every direction
• Connected to a CCD(charge coupled device) which converts x-rays to light so we can see an image
• Produces detailed, 3D images of organs or cross-sections
• Shows difference between soft and hard tissues
• More expensive than x-ray machine
• Higher dose of x-ray than x-ray machine

• Human range of hearing is 20Hz to 20000Hz
• Ultrasound is anything over 20000Hz
• Transducer connected to computer is used to process information
• Sound waves are partially reflected when they meet boundarys between different tissues
• Time taken to reach a boundary is recorded to calculate distance
• Non ionising and more accurate images

Distance(m)= speed(m/s) x time(s)

S = V X T

Used in pre-natal scanning and to break down kidney stones

Refraction-the changing of direction of light passing through one transparent medium to another
Refractive index- the measure of how much a substance can refract a light ray Sin(angle of incidence) / Sin(angle of refraction) = Refractive index The refractive index of a substance should always be the same regardless of angle, however measurement errors are likely A light ray travelling along a normal is not refracted.