Jumaat, 29 Januari 2010

Devices to overcome the limitations of sight.

Devices to overcome the limitations of sight.
1. Microscope
•Instrument to magnify object such as virus.
•Objective lens and eyepiece magnify image.Types- light microscope, electron microscope

2. Magnifying glass
•Limited magnifying power-10 to 15 times
•Use to see small object.
•Magnifying glass is convex lens.

3. Telescope
•viewing distant objects -stars, planets , Moon.
•Consists of two convex lenses- objective and eyepiece lens.
•The image produced by the objective lens is magnified by the eyepiece lens.

4. Binoculars
•Binoculars provide a stereoscopic vision of distant objects.
•The parts of the binoculars and their functions are the same as those of the telescope.
•Binoculars are actually a pair of telescope.
•Use- watch horses running in a race

5. Ultrasound scanning device
•ultrasonic waves - create images -organ , fetus.
•Device shaped like microphone is pressed against the area being scanned.
•This device sends out very high frequency sound waves into the area being scanned.
•The waves bounce back upon hitting an organ and an image of the organ is then obtained on computer screen

6. X-rays
•X-rays can also be used to detect the condition of certain organs or detect fracture of bones.In medical X-rays, the X-rays penetrate the internal soft body tissues and form images on a film which can be examined by a radiologist

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