Translations:Adventist Youth Honors Answer Book/Health and Science/Optics/59/en

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9. Construct one optical instrument using mirrors or lenses, such as a periscope, a slide or opaque projector, or a simple telescope.

Periscope

Principle of the periscope.
A - Periscope using two plane mirrors.
B - Periscope using two right–angled prisms.
1 - 2 - Plane mirrors.
3 - 4 - Right–angled prisms.
5 - 6 - Observer eye.
7 - 8 - Periscope tube.
H - Periscope optical height.
Different types of periscopes:
Lens periscopes. [1]
Handheld periscope. [2]
Submarine periscope.[3]

A periscope is an instrument for observation from a concealed position. In its simplest form it is a tube in each end of which are mirrors set parallel to each other and at an angle of 45° with a line between them.