Picture of Wii Sensor Bar IR lights
Curious as to how the Wii controller talks to the Wii? Thought the sensor bar took in all the data? You might be surprised to find out that the sensor bar doesn't receive data at all! The sensor bar actually sends out data. Well, not data exactly but infrared light. That light is then picked up the Wiimote which used that light to calculate how far away and in which direction the Wiimote is facing.
You can't see infrared light with the human eye because of the wavelength the light is at. Cameras can pick up this wavelength though. Check out the picture above to see the light as it is sent out of the sensor bar. Pretty neat, isn't it?