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Radiation in Medicane
using radiation to spot illnesses.
X-rays
CAT scans
PET scanners
Endoscopes
Ultrasound
using radiation for treatment.
Radiation therapy
Ultrasound
Lasers
Radiation energy
Radiation
Radiation intensity
I = P ÷ A
Reflection
specular reflection
diffuse reflection
Refraction
refraction doesn't occur when light rays cross into a different medium at 90o.
Total internal reflection
critical angle
The critical angle for most glass is about 42°.
Optical fibres
Light getting in at one end undergoes repeated total internal reflection, even when the fibre is bent, and emerges at the other end.
optical fibres are used in endoscopes that allow surgeons to see inside their patients
Refraction of light by lenses
Converging lenses
The distance from the focus to the middle of the lens is called the focal length.
Diverging lenses
To determine the focus for a diverging lens, you trace the path of the light rays that have left the lens backwards to the point at which they converge. The distance from this point to the middle of the lens is the focal length.
When an object is placed within the focal length of a diverging lens it is magnified and remains the correct way up.
The lens equation
1/focal length (m) = 1/object distance (m) + 1/image distance (m)
This can be rearranged to:
real image
virtual image
