The Light Sensor is one of the two sensors that give your robot vision [The Ultrasonic Sensor is the other]. The Light Sensor enables your robot to distinguish between light and dark. It can read the light intensity in a room and measure the light intensity of colored surfaces.

Suggestions for use
You can use the Light Sensor to make a burglar alarm robot: when an intruder turns on the light in your room the robot can react to defend your property. You can also use the Light Sensor to make a line-following robot or a robot that can sort things by color.

Detecting ambient [surrounding] light
Test the Light Sensor’s ability to read ambient light by measuring the light level in different locations of the room. For example, first hold the sensor against the window. Then hold it under the table. Watch how the readings differ.

Test it!
Test Light Sensor readings. Here’s how:

1. Connect the Light Sensor to the NXT.
2. Select the View submenu on the NXT display. Select the Light Sensor icon and the port where you have connected the sensor, and press the orange Run button.
3. Hold the Light Sensor up to the different colors on the test pad that came with your kit and see the different readings.

Try Me

The NXT comes with a Try Me function. Connect a Touch Sensor to port 1 of the NXT and select the Try Me submenu on the NXT to test your Light Sensor. You’ll get a fun reaction.