Week 4 Assignment Result Done by: Jap Xin Yi
Remote Control of Air Conditional • When we try to see the infrared signal from a remote control with our naked eyes, we can’t see it. This is obvious because infrared rays have wavelength by 10-7 m to 10-3 m which is beyond visible light wavelength of (4.0 – 7.5 ) x 10-7 m. • It seems there is a closer end of infrared wavelength to the visible end of the visible light. Perhaps we could see this very beginning side of the infrared. • Though we could not see it directly, we could see it through help of a devise. One way, we could see infrared as a flashlight through the digital camera. • In my opinion, I do not think the flashlight spot is caused by infrared ray. I think that it is only a visible light. • We cannot see the infrared ray because the wavelength of infrared ray is too high for human being to see. The receivers of our eyes called rods and cones will pick up the images that we have seen. Rods see black and white ; cones see color rays.
Remote Control of DVD Player • When we try to see the infrared signal of a remote control, we can’t see anything but we could detect the ray through an instrument such as digital camera as shown in the diagram below. • The human eyes are made up of receptors on retina that can detect light energy of certain wavelengths [(4.0 – 7.5 ) x 10-7 m]. The components that detect the visible light are the rod cells and cone cells. Human can only detect visible light which is only a small portion of the electromagnetic spectrum.
Remote Control of Door • A strange observation is the signal from a remote control of a door or gate can be seen with human naked eyes as well as detectable with the help of a digital camera. • Therefore, I want to ask Prof. if the door remote control signal is a combination of visible light and infrared ray? If it is, why do they want to make the remote control with this combination? • In my opinion, it is the combination of visible light and infrared ray because the rods and cones of human’s eye can only detect visible light. • According to the orthodox vision theory, the eye’s rods behave as transducers in that they convert light energy to electrical energy. The optic nerve transmits the electrical energy to the brain. To achieve this process, a minimal threshold electrical energy is required. The minimal threshold frequency and wavelength is that of red light. Below it, no electrons can be excited and then ejected from rod cells, and no minimal threshold electrical energy will be transmitted to the brain by the optic nerve. So, the visible light which has suitable wavelength and frequency could be seen.
Questions Can we divide infrared rays into a spectrum such as low infrared, medium infrared, and high infrared base on their wavelength at various length? If acceptable, could we say that the end nearer to visible red light could actually be visible to naked eye? Can we visualize microwave? If can, how? Through instrument? Could microwave wavelength be detected by a digital camera? Is a digital camera make up of chips that could detect infrared which a photographic film would do the same? Why should a digital camera detect infrared ? In what ways would it help the iamges beauty of a photograph?