Ionization smoke alarms are general y more
responsive to flaming fires.
How they work:
!
Ionization-type smoke alarms have a smal amount
of radioactive material between two electrical y
Stop-Drop and Roll
charged plates, which ionizes the air and causes
By BASF Jr. Reporter Georgina Beirne, Rutherford, NJ
current to flow between the plates. When smoke
enters the chamber, it disrupts the flow of ions,
thus reducing the flow of current and activating
the alarm.
Electrical
power source
+
Positive electrode
Alpha
Negative ion
source
Positive ion
Alpha particles
-
Negative electrode
Current
Alarm
detector
Photoelectric smoke alarms are general y more
responsive to fires that begin with a long period of
smoldering (cal ed "smoldering fires").
How they work:
IF A FIRE GOES ON, JUST STOP, DROP AND ROLL.
Photoelectric-type alarms aim a light source into a
sensing chamber at an angle away from the sensor.
The Science of smoke detectors
Smoke enters the chamber, reflecting light onto the
light sensor; triggering the alarm
You may not know it, but science helps us in our
Light source
daily lives every day. Sure, with medicine and
Lens
new research, but smoke detectors? Actual y, there
Light beam
is science behind how a smoke detector works.
Reflected light
In the fol owing paragraphs, I wil explain how
Alarm
science is combined in the smoke detector.
As you already know, smoke detectors are used
to alert you and your family when there is a high
Photo-cel
Lens
smoke build-up in your house. But there are two
Smoke particles
main types of smoke detectors. There are ionization
Light catcher
detectors and the photoelectric detectors.
Let's break this down, so it is easier to understand.
Take a look at how a smoke
detector works! Science is amazing!
16