P3 pt 1 (new spec)

P3 detailed mind map. Pt 2 out soon.

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  • Created by: Fatima
  • Created on: 26-02-14 20:41
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  • P3 pt 1
    • X-rays
      • X-rays are part of the electromagnetic spectrum. They have a very high frequency and a short wavelength. The size of the wavelength is the same order of magnitude as the diameter of an atom.
        • This gives the X-ray a very high energy content, which makes it ionising and therefore has the possibility to cause cancer.
      • Properties
        • Xrays affect photographic film in the same way as light does.
        • X rays are absorbed dense materials such as metal and bone
        • X rays are transmitted by soft tissue
      • X ray in medical practices
        • When you get an X ray taken, the X rays are transmitted by your soft tissue; however, your bone absorbs these x rays.
          • CCD (charged-couple devices )  form electronic images of X rays.
          • CT scans
            • patient is placed in a circular tube. Xrays a fired at one point and detected at the other
              • differentiates between soft and harder tissue and therefore produce a sharper clearer image, giving way to a more accurate diagnoses
    • moments (turning force)
      • N x m =  Nm
    • Hydraulics
      • Liquids are virtually incompressible
        • pressure = force / surface area
      • Hydraulics are force multipliers
        • force = surface area x pressure
          • Pressure doesn't change,  therefore as the surface area increases so does that force
    • optics
      • The eye
        • retina: light sensitive cells where the light rays focus on
        • cornea: provides a layer of protection and helps the light focus on the retina
        • lens: focus's light onto the retina
        • pupil: where the light enters the eye
        • iris : a ring of colored muscle that alters the size of the pupil, so enough light and not too much enters the eye.
        • suspensory ligaments and ciliary muscles: alters the size of the lens so that you can focus on things that are far and near. For example when you look up the ciliary muscle contract making your lens thinner so that you can focus on things further away.
      • Lenses
        • converging/convex
        • diverging/concave
        • how to describe and image:
          • magnified, diminished, real, virtual, upside down, upright
          • magnification = image / object
        • short sighted people: the 'near point' is before the retina. Caused by a long eyeball or a weak lens
        • Long sighted people: the 'near point' passes the retina. Caused by a short eyeball or a strong lens


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