Detects movement to perform a task such
as opening a door
How does it work?
A camera looks for movement and when
it detects it it performs the task
What is it?
A light sensor
What does it do?
When hit by light, it performs a task such as
switching a device on
How does it work?
It uses the photons in light to generate electricity
or to change properties such as electrical
resistance
What is it?
A gas sensor
What does it do?
Detects when there is harmful
gas in the air
How does it work?
It has free electrons that are attracted to the surface when there are a lot
of oxygen particles in the air. When there is mostly another gas, they are
free again and conduct a current to sound an alarm
What is it?
A temperature sensor
What does it do?
Senses the
temperature of an
object
How does it work?
A change in temperature alters the voltage of one type of sensor.
Others work because their resistance is changed by the temperature
or in other ways.
What is it?
A proximity sensor
What does it do?
Senses when an object is close
to it without contact
How does it work?
It emits infrared light and
detects how many rays are
reflected back. The more rays,
the closer the object