Science
Science 4 -Light
August 10, 2008
Journal Entry 1.
Fibre optic technology offers many advantages when used in medical applications.
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describe how optical fibre may be used in medical applications- In a medical Emergency when the doctor asks for a light to be shone on a target whithout a clear line of sight path.
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identify the traditional medical techniques that optical fibres might replace- Well instead of using mirrors and other reflective tools to bend light when now they can just optical fibres.
- Evaluate the benefits of fibre optic technology to medicine. – The benefits of the optic technology is that the light can go further and places that were once inexecible.
August 10, 2008
Journal Entry 2
Investigate the two types of sight defect- long-sightedness and short sightedness.
Find the following information:
Long sitedness-
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What Causes The Defect- The cause of long sightedness is unknown but it is known that the eyeballs of longsighted people are smaller then the average.
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The Symptons Displayed- Some Causes of longsightedness are – Blurry Vision from long distances, headaches & tiredness.
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Propose What Sort Of Lens May Be Used To Correct Each Vision- A convex lens because it assists focuse to the retina by bending light onto it.
Short sitedness-
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What Causes The Defect- Myopia or short sitedness is usually caused if it runs in your family or if your cornea is to curved or your eyeball is to long.
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The Symptons Displayed- If objects are close and they look distorted and blury.
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Propose What Sort Of Lens May Be Used To Correct Each Vision- A concave lens should be used because the rounder the lens the more the light rays will be bent inwards to help the retina.
August 10, 2008
Journal 3
- Analyse why red sunsets can sometimes be more impressive when there is more dust or pollution in the air than usual.
- Describe what happens inside water droplets to cause a rainbow and explain how you can tell whether a rainbow is a primary or secondary.
Answers-
1. Taken from http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/redsun.html
Sunsets are reddened because for sun positions which are very low or just below the horizon, the light passing at grazing incidence upon the earth must pass through a greater thickness of air than when it is overhead. Just before the sun disappears from view, its actual position is about a diameter below the horizon, the light having been bent by refraction to reach our eyes. Since short wavelengths are more efficiently scattered by Rayleigh Scattering, more of them are scattered out of the beam of sunlight before it reaches you. Aerosols and particulate matter contribute to the scattering of blue out of the beam, so brilliant reds are seen when there are many airborne particles, as after volcanic eruptions.
2. Quoted from http://www.weatherquestions.com/What_causes_rainbows.htm
Rainbows are caused by the splitting of white sunlight into it component colors by raindrops. Some of the light that falls on a water drop enters the drop. As it enters the drop, the light is bent (refracted) and split into a rainbow of colors. This is because each color of light gets bent by a slightly different amount. The different colors then reflect off the back of the drop, and when they pass through the front of the drop again, they are bent (refracted) still more. A rainbow is always directly opposite the sun from the observer. This explains why rainbows are only seen when the sun is low in the sky, usually in the late afternoon. The rainbow’s location will appear different for observers at different locations, but it is always directly opposite the sun. 
