hum

hum

Electronics an undesired low-frequency noise in the output of an amplifier or receiver, esp one caused by the power supply

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

hum

[həm]

(electricity)

A sound produced by an iron core of a transformer due to loose laminations or magnetostrictive effects; the frequency of the sound is twice the power line frequency.

(electronics)

An electrical disturbance occurring at the power supply frequency or its harmonics, usually 60 or 120 hertz in the United States.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Hum

 

the name given during the Middle Ages to the region between Dubrovnik and the Neretva River. The earliest surviving reference to Hum dates from the 10th century and describes the region as subject to the Serbian prince Mihajlo Višević. Late in that century the region became part of Samuil’s state, and in 1018 it fell under Byzantine control. Hum became part of Zeta in the second half of the 11th century, part of the Nemanja state in the late 12th century, and part of Bosnia in the 1320’s. Duke (herceg) Stepan Vukčić took control of Hum in the 1440’s. The duke’s dominions, of which Hum constituted a major part, became known as Hercegovina in the mid-15th century.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.