Electromagnetic Spectrum Activity - Infrared
- NASA EM Spectrum Information Pages Infrared
- Discovery Education EM Spectrum
- List of SI (metric) prefixes . e.g. nano, milli, mega, tera.
You know infrared radiation as 'heat'. Warm objects emit infrared energy. Infrared is light that is below the frequency that humans can see with their eyes. We can sense it with our skin. Some creatures such as snakes can make images from infrared energy as human eyes make images of light energy. This is very useful at night when tracking your rodent prey.
Infrared energy is emitted by objects due to the movement of electrons and protons in the object. This is called thermal radiation. The incandescent light bulb emits 90% of its total energy in the infrared range. What band of EM spectrum does the light bulb emit most of its energy in?
In nature anything warm is an infrared source. Sunlight at the Earth's surface has as much infrared energy as visible light energy.
Human uses for infrared include heating, such as a heat lamp at a restaurant or in your bathroom, and imaging, for example night vision goggles and home heat-loss sensors. Infrared is also used for communication, that is when you can find the remote control.
With shorter wavelengths it is more common to refer to the wave's wavelength rather than its frequency. Infrared frequencies cover a range of 1 THz to 430 THz. A low frequency wave has a large wavelength. The relationship is defined as:
- Variables: λ=wavelength (m) v = speed of light (3 x 108 m/s) f = frequency (Hz). Note THz = 1 x 1012
- Formula: λ = v ÷ f
- Example: λ = 3 x 108 m/s ÷ 100 THz = 3 µm
IR has more energy than microwaves but less than visible light. Infrared is non-ionizing radiation. Ionizing radiation has enough energy to tear electrons away from their atoms. The atoms are now 'ions'. These ions can cause unwanted chemical reactions in a material or organism.
EM Spectrum Data Table
ionizing/ med / lo
- Electromagnetic waves
- Radiation consisting of waves of energy sent through space and matter associated with electric and magnetic fields resulting from the acceleration of an electric charge (light, x-rays, microwaves, gamma rays, etc.). 3.9
- The number of back-and-forth cycles per second, in a wave or wave-like process. 3.5
- The time for one wavelength to pass a point. The time for a wave to travel the distance of one wavelength. P= 1/frequency. 3.5
- A rhythmic disturbance that transfers energy from place to place. 3.5
- The distance measured from crest to crest of one complete wave or cycle. 3.5