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In the past radioactive materials were used to give a permanent glow to see-in-the-dark items like wrist-watches. These materials are now regarded as hazardous and are no longer used.
M
Magnification
Light: Making something look larger. An object can be magnified by using a convex lens – a lens that bulges out in the middle. If the lens is held close to the eye, an upright, magnified image can be seen.
 Magnification – A magnifying glass will often give a magnification of up to 2. For greater magnification, say to 20 or 30 times,
a hand lens can be used. This is the kind of magnifier used by people such as biologists and geologists for field science. Even higher- powered magnification requires the lens to
be mounted in a fixed frame because high magnification lenses have a very shallow depth of focus and so need to be focused carefully. The result is the microscope.
Magnified images are used in microscopes and telescopes. Eyeglasses are not usually used to provide much magnification. Their job is to make it easier to see an object clearly, and that usually just means focusing it properly.
Sound: Making something sound louder by using an amplifying system.
Eyepiece
Microscope
An instrument for observing objects in detail. Microscopes use a number of lenses to achieve very high levels of magnification. They also use mirrors to ensure that light can be directed onto
the subject being observed. In this way a bright, highly magnified image is achieved.
Mid-range
The size of loudspeaker used for reproducing the middle range of sound. The cone is normally about 6 to 10cm across. (See also: Tweeter and Woofer.)
 Microscope – This is a simple optical microscope.
Objective lenses with a range of magnifications in a rotating block so that the user can switch from one to another
The thing being viewed is held on a specimen table in the focal plane for the lenses.
A lens is used to concentrate the reflected light source onto the thing being viewed.
A mirror is used to reflect the light source up into the specimen.
Mid-range
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