# Physics P3 AQA Medical Applications of Physics

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• Medical Applications Of Physics
• X-rays
• X-rays are part of the electromagnetic spectrum. They have a short wavelength and cause ionisation
• Properties
• They are transmitted by soft tissue
• Absorbed by metal and bone
• Their wavelength has the diameter of an atom
• They affect a photographic film in the same way as light
• Used to diagnose medical conditions and treat them
• Precuations should be taken as they are ionising
• An example is a C.T scan. They form a three d image as they take slices of x-rays
• Ultrasound
• Higher frequency than human hearing (20-20,000 hertz)
• Ultrasound waves are partially reflected when hitting different densities.
• The time taken for the reflection to reach a detector determines how far away the bondary is.
• s=v*t
• Used in medicine- pre-natal scanning and removing kidney stones.
• Lenses
• Refraction is the change of direction in lightas it passes into a different medium.
• A lense forms an image by refracting light
• In converging/convex lenses parallel rays of light are brought to a focus called the focal length
• refractive index=sini/sinr
• Images; are they real/unreal, magnified/not magnified, upright/inverted
• Converging lense=magnified
• Ray diagrams: through principle axis, through centre and where they meet
• Magnification= image height/object height
• The Eye
• Parts of the eye
• Cornea- Focus' the light
• The lens allows the light to be refracted
• Pupil- allows the light to enter the eye
• The retina- detects light and transmits it to the brain
• The Caliary Muscle- These tighten the thickness
• Suspensory ligaments- these attach the cornea to the claiary muscles
• Concave/Convex lenses help to improve the image on the retina
• Near point-       25cm                            Far point-infinity
• The eye and a camera work in the same way as they both allow light in and the photographic paper acts in the same way as a retina.
• Power of a lense P=1/f p is dioptres and focal lenght is metres
• Other uses of light
• Total internal reflection- refractive index=1/sinc
• Crotical angle is where the refracted ray disappears
• Light can be sent along optical fibres
• Endoscopes send light down a tube in order to see.
• Makes surgery much easier
• Lasers can be used for cutting,cauterising and burning

## Comments

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This is another good mind map for the topic of medical physics, but this is especially suited for students who are studying the Triple Science AQA qualification .

Mind maps are a great way to order your learning and help you remember the key points.

Once you have completed this mind map, you can test yourself to see how much you have learnt.

There is a lot of information you can extract from this mind map. Enjoy!

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