Why can't we see light emitted from TV remote but camera can ?

Remember that battery test we used to do to check whether batteries are working or not. We simply put them into TV remote and check the light coming from IR blaster(LED of remote). but ever wondered how the camera can see but we can't?

You can see red color IR from diode of TV remote from camera sensor but your naked eyes can't see them. To understand this let's take a look on working of our eyes and camera sensors. Human eyes can detect (see) 3 basic colors RGB. According to their wavelength, they classified as small, medium and large.

Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers (nm) to 1 millimeter (mm). A typical Human cone cell (colors) can't detect (see) above 700nm. these lights are known as non-visible lights. Hence our eyes can't detect or see Infra Red light.

What about the image sensor of a camera? camera image sensors are highly sensitive to lights while working at room temperature. they have wide coverage of light spectrum. hence they can detect nob visible lights too. 

Along with this, there is a filter mounted on top of camera sensors known as Bayer Filter. It improves light detection capability of sensor and reproduction of lights. That's why image sensors are extremely sensitive to visible as well as non-visible lights.