4. Fibre optic periscope is used for transport purpose.
Answers
Answer:
Periscopes allow a submarine, when submerged at a relatively shallow depth, to search visually for nearby targets and threats on the surface of the water and in the air. When not in use, a submarine's periscope retracts into the hull.
Explanation:
Answer:
Periscope, optical instrument used in land and sea warfare, submarine navigation, and elsewhere to enable an observer to see his surroundings while remaining under cover, behind armour, or submerged.
Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables.
Fiber optics work on the principle of total internal reflection. Light reaching the boundary between two materials is reflected such that it never leaves the first material.
NMAH | Navigation | Telescope. Sailors use telescopes of long-focal length to sight distant ships and landfalls. Most eighteenth-century telescopes of this sort had draw tubes made of wood or carboard. Nineteenth-century instruments were made with brass draw tubes covered with rope, wood or canvas.