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Light Meter
Building: Easy


Building Instructions




Connect the Color Sensor to port 3 on the NXT.

Light Meter Programming
Download Programs (help)

The LightMeter program can be used on any robot that has the Color Sensor connected to port 3 (and is easily modified for other ports if necessary).  With the sensor-on-a-stick design above, you can easily point the sensor in any direction, or point it down to measure surfaces, using the gray angled beams to help keep a consistent distance from the surface.  For any other robot using a Color Sensor in Light Sensor mode (such as the Line Follower), you can simply use the LightMeter program as-is to measure sensor readings seen by that robot.

The brightness readings are continuously updated on the NXT screen.  To toggle the sensor's LED illumination on and off, press the Left Arrow button.  To rotate between Red, Green, and Blue LED illumination, press the Right Arrow button.


  • Run a series of experiments to collect readings on different surfaces and also with the sensor pointed at various objects.  For example, it is possible to get a reading of 100 by pointing the sensor at a bright light.  It is possible to get a 0 reading by turning off the LED illumination and putting your thumb over the sensor.  What about reflection from different surfaces?  How do the color of the surface and how shiny it is affect the readings?  What about the distance of the sensor from the surface?

  • When measuring reflected light, the readings will depend a bit, or maybe a lot, depending on which color LED is used.  For example, a red surface will reflect red light much better than a green surface.  Can you explain the results you see?

  • Using the numeric results you get, can you design an effective use of the Color Sensor in Light Sensor mode such as the use in the Line Follower project?


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