Q&A: General Astronomy and Space Science
What are the different types of EMR and what are they used for?
There are many kind of electromagnetic radiation and they are distinguished by
their wavelengths if you consider EMR as waves.
You can also think of electromagnetic radiation as consisting of particles of light,
called photons, and each photon has a certain amount of energy associated with
it. Each energy corresponds to a different type of EMR. High energies correspond
to short wavelengths.
Let's think of EMR as waves for our discussion. Scientists group together
certain wavelengths into catagories, for example visible light is the group
of wavelengths from 400 nanometers to 700 nanometers. This is the energy
band (or grouping) that our eyes are sensitive to.
Shorter wavelengths are grouped together as ultraviolet radiation, the
band that gives us sunburns! And even shorter wavelengths are grouped
together as x-rays. X-rays can be used in many different ways, but 2 of
the most important ways are medical x-rays and x-ray telescopes like
For a medical x-ray, a beam of x-rays is sent towards a human being (let's
say towards a tooth) and a special plate is set behind the tooth to catch the
x-rays after they pass through. This gives a picture of the tooth including
any cracks or cavities in it. So it is a type of x-ray picture.
More at http://chandra.harvard.edu/xray_astro/medxray.html
X-ray telescopes on the other hand are big x-ray buckets, catching x-rays
that are emitted from objects in the universe. Since x-rays have short
wavelenths, and therefore high energies, telescopes like Chandra are most
sensitive to hot (high energy) objects and processes.
More at http://chandra.harvard.edu/xray_astro/xrays.html
An example of longer wavelength EMR is the group we call radio waves, which
are familiar to you from listening to the radio.
Another explanation of this may be found on a NASA website at: