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Applications of total internal reflection
a) A prism periscope
It makes use of two right-angled isosceles prisms. The light from the object is inverted through 900 by the first prism and a further 900 by the second prism.
This periscope produces brighter images compared to those of the simple periscope in which a plane is used. The image formed is erect and virtual. A prism periscope has the following advantages over the simple periscope:
- Forms brighter and clearer images. A simple periscope produces many faint images besides the main
image especially if the mirror is thick.
- Does not absorb the energy of the light. Plane mirrors absorb some light incident on them.
- Has a tough structure and thus does not easily wear. The painting on the plane mirror can wear out with time.
b) A prism binoculars
This device is used to reduce the distance between the eyepiece and the objective thereby reducing the length of the telescope. It forms an erect image.
Objective lenses
Eyepiece lenses
c) Optical fibre
It is a thin flexible glass rod made up of two parts; the inner part made of glass of higher refractive index and the outer glass coating of lower refractive index. When a ray of light enters the fibre at an angle greater than the critical angle, it undergoes a series of total internal reflection before it finally emerges from the other end. None of the light energy is lost in the process.
Optical fibres are used in medicine for viewing internal body organs (the endoscope) as well as in
telecommunication. They are preferred to ordinary cables because they are light and thin and do not cause scattering of the signals.
chrispohmomanyi answered the question on February 9, 2018 at 06:23
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