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Alarm facts for kids

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Smoke detector
Smoke detector

An alarm device or system of alarm devices gives an audible, visual or other form of alarm signal about a problem or condition. Alarm devices are often outfitted with a siren.

The word came from the Old French A l'arme meaning "To the arms", "To the weapons", telling armed men to pick up their weapons and get ready for action, because an enemy may have suddenly appeared.

Alarm devices include:

PDphotos-org alarm clock 1 bg 050304
Alarm clock
  • burglar alarms, designed to warn of burglaries; this is often a silent alarm: the police or guards are warned without indication to the burglar
  • alarm clocks can beep, buzz or ring off as an alarm at a set time to wake a person up or for other reminders
  • safety alarms, which go off if a dangerous condition occurs. Common public safety alarms include:
    • civil defense siren also known as tornado sirens or air raid sirens
    • fire alarm systems
    • smoke detector
    • car alarms
    • autodialer alarm, also known as community alarm
    • personal alarm
    • Video Alarm Verification System provides instant notifications upon the detection of a possible threat verified through a video feed

Alarms have the capability of causing a fight-or-flight response in humans; a person under this mindset will panic and either flee the perceived danger or attempt to eliminate it, often ignoring rational thought in either case. A person in such a state can be characterised as "alarmed".

With any kind of alarm, the need exists to balance between on the one hand the danger of false alarms (called "false positives") — the signal going off in the absence of a problem — and on the other hand failing to signal an actual problem (called a "false negative").

Personal alarm
Personal alarm

False alarms can waste resources expensively and can even be dangerous. For example, false alarms of a fire can waste firefighter manpower, making them unavailable for a real fire, and risk injury to firefighters and others as the fire engines race to the alleged fire's location.

In addition, false alarms may allow people to ignore alarm signals, and to possibly to ignore an actual emergency: Aesop's fable of The Boy Who Cried Wolf is an example this problem.

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