Kinect the dots – applying knowledge of EM waves

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Kinect the dots – applying knowledge of EM waves

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Image: popculturegeek.com

The story

The latest must-have gaming gadget was released in the UK last week.  Microsoft’s Kinect for the Xbox allows gamers to interact with a games console in a completely new way.

This device allows you to play games without a controller by using body movements and gestures.  If you have no idea what Kinect is all about (but I’m positive your students will) check out the video below.

Teaching ideas

I’m not suggesting you use the Kinect in the classroom but the way it works can be used to take a topical and interesting look at EM waves.

The device sends out thousands of tiny infra-red dots which reflect off objects in the room.  It then uses the time it takes for the wave to return, as well as any changes in the wavelength, to work out what the space looks like.  It can detect which objects are people from recognising shapes and calculate where limbs will be in a few microseconds.  Pretty clever tech for under £150 I’m sure you agree.

You could introduce the device as a plenary to the end of a lesson on EM waves.  You can show students the video taken using an IR camera from the weblink below and ask them what it shows.  Some of them may have played a game using the Kinect and can share with the rest of the class what the experience is like.  They can then apply what they know about EM waves to explain how the device can tell where your arms and legs are and where they have moved to.

You can also ask them why IR is used in the Kinect rather than radio, light or UV waves.  Obviously, UV is not used because of the dangers associated with it and if visible light was used then the ambient light would affect the device.  I am speculating here (and please can someone put me right if I am wrong) that IR waves are used instead of radio because they have a much shorter wavelength so any minute changes would be more easily detected.

The speed equation (speed = distance/time) can be used to work out the distance someone is standing from the device if the IR beam takes 0.00000002 seconds from the time it left the device to the time it returns.  (answer at the bottom of the post!)

Has anyone used any other interesting applications of EM waves in lessons? Please share using the comments section below.


Post from the Wired blog on how Kinect works

Spooky video which shows how the device works using an IR camera.

Answer:  The person is standing 3 m away.  0.00000002 s x 300000000 m/s (speed of all EM waves) = 6 m.  This is the distance the beam has to travel to the person and back again.