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TEACHER BACKGROUND:
ELECTROMAGNETIC RADIATI0N
When we look at the world around us we are seeing visible light waves (or
visible radiation). However, there are many other forms of radiation that we
cannot see with our eyes. These types include gamma rays, x-rays,
ultraviolet, infrared, microwaves and radio waves. Together with visible
light, all these types of radiation make up what we call the electromagnetic
spectrum - the complete spectrum of radiation. Light (or radiation) is made
up of vibrating waves of electrical and magnetic fields. This is where the
term electromagnetic radiation comes from. Electromagnetic radiation
travels in waves that have different wavelengths, energies and frequencies.
Wavelength and Frequency
The wavelength is the
distance between individual
waves (e.g. from one peak
to another). The
wavelengths of visible light
range from 400 to 700
billionths of a meter. But
the entire electromagnetic
spectrum extends from one
billionth of a meter (for
gamma rays) to meters (for
some radio waves). The
frequency is the number of
waves which pass a point in
space each second. Visible light frequencies range between 430 trillion
waves per second (red) and 750 trillion waves per second (violet). The entire
electromagnetic spectrum has frequencies between less than 1 billion waves
per second (radio) and greater than 3 billion waves per second (gamma rays).
Light waves are waves of energy and the amount of energy in a wave is
proportional to its frequency. Wavelength increases, while frequency and
energy decreases as we go from gamma rays to radio waves.
