A commutated DC motor has a set of rotating windings wound on an armature mounted on a rotating shaft. The shaft also carries the commutator, a long-lasting rotary electrical switch that periodically reverses the flow of current in the rotor windings as the shaft rotates. Thus, every brushed DC motor has AC flowing through its rotating windings. Current flows through one or more pairs of brushes that bear on the commutator; the brushes connect an external source of electric power to the rotating armature.
What does the communicator do?
reverses the flow of current in the rotor windings

In the year 743 the synod in Leptines (Leptines is located near Binche in Belgium) spoke out furiously against the excesses in the month of February. Also from the same period dates the phrase: "Whoever in February by a variety of less honorable acts tries to drive out winter is not a Christian, but a pagan." Confession books from around 800 contain more information about how people would dress as an animal or old woman during the festivities in January and February, even though this was a sin with no small penance. Also in Spain, San Isidoro de Sevilla is written complaint in the seventh century that people coming out into the streets disguised in many cases the opposite gender.
What was it a sin with no small penance to dress up as?
an animal or old woman

Computers control functions at many utilities, including coordination of telecommunications, the power grid, nuclear power plants, and valve opening and closing in water and gas networks. The Internet is a potential attack vector for such machines if connected, but the Stuxnet worm demonstrated that even equipment controlled by computers not connected to the Internet can be vulnerable to physical damage caused by malicious commands sent to industrial equipment (in that case uranium enrichment centrifuges) which are infected via removable media. In 2014, the Computer Emergency Readiness Team, a division of the Department of Homeland Security, investigated 79 hacking incidents at energy companies.
What department does the Computer Emergency Readiness Team belong to?
the Department of Homeland Security