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The Ultimate Motion Sensor and Burglar Alarm Quiz
by Staff
Ever wonder how motion sensor lights and burglar alarms work? Take this quiz and learn how motion sensors and burglar alarms detect intruders.

Why do they have those electronic devices at store entrances?

  • to let the store staff know that someone has entered
  • to emit a sound if someone leaves with unpaid goods
  • both of the above

A photosensor works by facing a beam of light. When someone walks through and breaks the beam:

  • the photosensor notes the change in the light of the beam and rings a bell.
  • the photosensor picks up the color from their clothing and rings a bell.
  • the photosensor picks up their vibrations and rings a bell.

An automatic door opener that uses radar sends out a burst of microwave radio energy. How does this make the door open?

  • A person walks past, reflects heat and thus causes the door to open.
  • A person moves into the field of energy, bounces back energy and causes the radar to respond by opening the door.
  • A person goes by, absorbs the energy and then causes the door to open.

How does a motion sensor using ultrasonic sound waves work?

  • It emits sound waves towards an object and notes the time involved in their reaching their target.
  • It reflects sound waves off an ultrasound machine and picks up vibrations.
  • It bounces the sound waves off a target and detects the echo.

Are motion sensors that detect infrared energy active or passive systems?

  • active
  • passive
  • in a sense, both

What is the range of sensitivity of infrared sensors?

  • five to eight micrometers
  • seven to 10 micrometers
  • eight to 12 micrometers

Why does a motion sensor detect only rapid change, such as a person walking?

  • because it is designed that way
  • because it is faulty
  • because it is not very sophisticated

How does a motion sensing light have a wide field of view?

  • It is due to the nature of infrared emissions.
  • It is due to the lens covering the sensor.
  • It is due to the energy that is found in the air.

Why can't a motion-sensing burglar alarm detect a burglar outside your window staring at you?

  • because it's probably nighttime
  • because the burglar isn't moving
  • because glass is not transparent to infrared energy

What does infrared energy have to do with greenhouses?

  • It has nothing to do with them; this is a myth.
  • The glass exterior blocks the infrared energy emitted by the plants, causing the heat to be trapped inside.
  • The glass emits infrared waves, which are absorbed into the greenhouse.