Why Do Automatic Doors Open as You Walk Up?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do automatic doors open as you walk up?

The Big Idea

Automatic doors open as you walk up because a sensor notices you! It sits above the door and watches the space in front. When something moves in, it tells the motor to open.

Watching Beam

Step one: a watching beam. Many automatic doors have a sensor above them that sends out a beam of invisible light or radio waves. The beam covers an area in front of the door, like an invisible doormat.

Notice Movement

Step two: notice movement. When you walk into the beam's area, the sensor notices something moving. It signals the motor to open the door.

Close Again

Step three: close again. After no one is there for a moment, the door closes. Some doors use a pressure mat in the floor instead, which notices your weight when you step on it.

A Closer Look

Let's take a closer look! The sensor does the sensing, looking for anything that moves. A simple program does the deciding. The motor does the opening. A floor mat is an older way to notice weight.

Quick Facts

Quick facts! Doors also have safety sensors so they do not close on people. Stores and hospitals use them so hands stay free. Radar sensors can notice even small motions. Stay clear of closing doors, and walk through calmly.

Think Like a Scientist

Now, give it a go! At a store with a grown-up, look above an automatic door for the sensor box. Walk up slowly, then quickly. Does the door open at the same distance? Where does the sensor look?

Outro

A sensor and a simple program open the door. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!