A digital camera, webcam, or digital camcorder
Television remote control
1. Turn on your camera and look through the view finder.
2. Point the front of your remote at the lens of the camera.
3. Now, push a button on the remote.
4. Did you see something? Can you see it when you're not looking through the camera?
Weird huh? Our eyes can only see a small part of the electromagnetic spectrum and the part that we can see, we call light. The camera sees slightly more of the electromagnetic spectrum than we can so it can detect infrared light. The camera then changes this light into a light frequency that we can see and lo and behold, there it is! We can see the invisible! Now if it could only find my keys!