Extra Credit by Robert Warren

1 of 7

Extra Credit

Published on Nov 18, 2015

No Description

Game boards have rules
a mixture of the two, and usually have a goal that a player aims to achieve.
Early board games represented a battle between two armies, and most current board games are still based on defeating opposing players in terms of counters, winning position, or accrual of points (often expressed as in-game currency).

a type of steel fencing wire constructed with sharp edges or points arranged at intervals along the strand(s).
Barbed wire was used in both of the world wars
It is used to construct inexpensive fences and is used atop walls surrounding secured property. It is also a major feature of the fortifications in trench warfare (as a wire obstacle).

Alexander Graham Bell made telephone
the early years from 1844 to 1898, from conception of the idea of an electric voice-transmission device, to failed attempts to use "make-and-break" current, to successful experiments with electromagnetic telephones by Alexander Graham Bell and Thomas Watson, and finally to commercially successful telephones in the late 19th century.

Photo by bulliver

Several possible methods of wireless communication were considered, including inductive and capacitive induction and transmission through the ground, however the method used for radio today exclusively involves the transmission and reception of electromagnetic waves.
After early speculation on the subject, experimental work on the connection between electricity and magnetism began around 1820 with the work of Hans Christian Orsted and continued with the work of André-Marie Ampère, Joseph Henry, and Michael Faraday.

Photo by bcostin

A submarine is a watercraft capable of independent operation underwater.
The term most commonly refers to a large, crewed, autonomous vessel.
Submarines were first widely used during World War I (1914–1918), and now figure in many large navies.

An escalator is a moving staircase
The device consists of a motor-driven chain of individual, linked steps that move up or down on tracks, allowing the step treads to remain horizontal
Escalators are used around the world to move pedestrian traffic in places where elevators would be impractical