Even though we can't see the infrared waves, they are always there. The visible light waves drawn on this picture are green, and the infrared ones are pale red. This image was taken with special film that can detect invisible infrared waves. This is a false-color image, just like the one of the cat.
False-color infrared images of the Earth frequently use a color scheme like the one shown here, where infrared light is mapped to the visible color of red. This means that everything in this image that appears red is giving off or reflecting infrared light.
This makes vegetation like grasa and trees appear to be red. The visible light waves drawn on this picture are green, and the infrared ones are darker red.
This is an image of Phoenix, Arizona showing the near infrared data collected by the Landsat 5 satellite. The light areas are areas with high reflectance of near infrared waves. The dark areas show little reflectance. What do you think the black grid lines in the lower right of this image represent? This image shows the infrared data appearing as red composited with visible light data at the blue and green wavelengths. Its range extends from fairly small wavelengths near the color red, x10 -9 m , to nearly a millimeter, 3x10 -4 m.
Even though infrared radiation cannot be seen by the human eye, it can definitely be felt. Infrared energy is felt as heat because it interacts with molecules by exciting them, causing them to move faster which increases the internal temperature of the object absorbing the infrared energy. Although all wavelengths of radiant energy will heat surfaces that absorb them, infrared radiation is most common in daily life because of the "ordinary" objects that emit it as radiant heat see blackbody radiation and Wien's Law for more information on this.
Read more about this imbalance here. Since the infrared spectrum is of lower energy than visible light, this limits the amount of solar energy that can be harnessed with standard photovoltaic cells. The shorter "near-infrared" waves, which are closer to visible light on the electromagnetic spectrum, don't emit any detectable heat and are what's discharged from a TV remote control to change the channels. The longer "far-infrared" waves, which are closer to the microwave section on the electromagnetic spectrum, can be felt as intense heat, such as the heat from sunlight or fire, according to NASA.
IR radiation is one of the three ways heat is transferred from one place to another, the other two being convection and conduction. Everything with a temperature above around 5 degrees Kelvin minus degrees Fahrenheit or minus degrees Celsius emits IR radiation.
The sun gives off half of its total energy as IR, and much of the star's visible light is absorbed and re-emitted as IR, according to the University of Tennessee. Household appliances such as heat lamps and toasters use IR radiation to transmit heat, as do industrial heaters such as those used for drying and curing materials.
Incandescent bulbs convert only about 10 percent of their electrical energy input into visible light energy, while the other 90 percent is converted to infrared radiation, according to the Environmental Protection Agency.
Infrared lasers can be used for point-to-point communications over distances of a few hundred meters or yards. The receiver converts the light pulses to electrical signals that instruct a microprocessor to carry out the programmed command. One of the most useful applications of the IR spectrum is in sensing and detection. All objects on Earth emit IR radiation in the form of heat. This can be detected by electronic sensors, such as those used in night vision goggles and infrared cameras.
A simple example of such a sensor is the bolometer, which consists of a telescope with a temperature-sensitive resistor, or thermistor, at its focal point, according to the University of California, Berkeley UCB.
If a warm body comes into this instrument's field of view, the heat causes a detectable change in the voltage across the thermistor.
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