signalling apparatus
51Electromagnetic interference — RIV redirects here. For other uses, see RIV (disambiguation). Electromagnetic interference in analog TV signal Electromagnetic interference (or EMI, also called radio frequency interference or RFI) is disturbance that affects an electrical… …
52Timeline of radio — The timeline of radio lists within the history of radio, the technology and events that produced instruments that use radio waves and activities that people undertook. Later, the history is dominated by programming and contents, which is closer… …
53Relay — This article is about the electrical component. For other uses, see Relay (disambiguation). Automotive style miniature relay, dust cover is taken off A relay is an electrically operated switch. Many relays use an electromagnet to operate a… …
54New York City Subway — Top: A number 4 train made up of R142 …
55Nice (WIPO) — The Nice Classification of Goods and Services is an Agreement resulting from the Diplomatic Conference of 1957 in Nice, France, and is updated every five years. It is an authoritative classification of goods and services for use in registering… …
56Diving equipment — Surface supplied commercial diving equipment on display at a trade show Diving equipment is equipment used by underwater divers for the purpose of facilitating diving activities. This may be equipment primarily intended for this purpose, or… …
57Mihajlo Idvorski Pupin — Born October 4, 1858 …
58List of EMC directives — The following list outlines a number of EMC standards which are known at the time of writing to be either available or have been made available for public comment. These directives attempt to standardize product safety and performance, in respect …
59Cell nucleus — HeLa cells stained for the cell nucleus DNA with the Blue Hoechst dye. The central and rightmost cell are in interphase, thus their entire nuclei are labeled. On the left, a cell is going through mitosis and its DNA has condensed ready for… …
60Steam locomotive — A steam locomotive is a locomotive powered by steam. The term usually refers to its use on railways, but can also refer to a road locomotive such as a traction engine or steamroller.Steam locomotives dominated rail traction from the mid 19th… …
