P3 | Mindmap

Medical applications of physics
1. X rays
  1. X rays are used to make CT scans and to destroy tumours at or near the body surface
  2. X rays can damage living tissue that they pass through
  3. X rays are absorbed more by bones and teeth than by soft tissue
  4. CT scans show the boundries between different types of soft tissue
2. Ultrasound
  1. Ultrasound waves are sound waves above 20000Hz
  2. Ultrasound is used for scanning and the destruction of kidney stones
  3. Ultrasound is partially reflected at a boundry between types oftissue
  4. Safer than X rays
3. Refractive index
  1. Refractive index is a measure of how much a substance can refract a light ray
  2. Refractive index = sin angle of incidence / sin angle of refraction
4. Endoscope
  1. The critical angle is the angle of incidence of a light ray in a transparent substance that causes refraction along the boundry
  2. Total internal reflection happens when the angle of incidence is greater than the critical angle
  3. An endoscope is used to directly see inside the body
5. Lenses
  1. A convex lens focuses parallel rays to the principal focus
  2. A concave lens makes parallel rays spread as if they came from the principal focus
  3. A real image is formed by the convex lens if the object is further away than the principal focus
  4. A virtual image id formed by the concave lens and if the object is closer than the principal focus from a convex lens
6. The eye
  1. Light is focused on the retina by the cornea and the lens
  2. The normal human eye has a range of 25cm to infinity
  3. Short sighted people can only see near objects clearly
Using magnetic feilds to make things work
1. Elecromagnets
2. The motor effect
3. Electromagnetic induction
4. Transformers
5. Case study
Using physics to make thingss work
1. Moments
  1. A moment is the turning force of an object
  2. To increase the moment, increase the force or increase the distance from the pivot
2. Center of mass
  1. The center of mass of an object is the point where the mass may be thought to be concentrated
  2. When an object is suspended at equilibrium, the center of mass is directly below the point of suspension
  3. The center of mass of a symetrical object is along it line of symmetry
3. Moments in balance
  1. For an object in equilibrium, the anticlockwise moment and the clockwise moments are equal
4. Stability
  1. A wider base increases stability
  2. Lower center of mass increases stability
5. Hydraulics
6. Circular motions
7. Pendulums

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