The electromagnetic spectrum includes the following regions, in order from long wavelength and low frequency to short wavelength and high frequency:
radio waves: 0.01 to 100 meters in length, 10^6 to 10^10 Hz in frequency
microwaves: 10^(-4) to 0.01 m, 10^10 to 10^12 Hz
infra red radiation: 10^(-6) to 10^(-4) m, 10^12 to 10^14 Hz
visible light: 10^(-7) m, 10^14 Hz
ultra violet radiation: 10^(-8) to 10^(-7) m, 10^15 to 10^16 Hz
X-rays: 10^(-11) to 10^(-9) m, 10^16 to 10^18 Hz
gamma rays: 10^(-14) to 10^(-12) m, 10^19 to 10^22 Hz
I've attached an image that shows this on a number line.
All electromagnetic radiation travels at the same speed, c=3.0 x 10^8 m/sec. Wavelength and frequency are inversely proportional:
c = (wavelength) x (frequency)
Energy is directly proportional to frequency.
Wavelength is the distance from crest to crest on a wave, and frequency is the number of cycles that occur in a given period of time. The unit Hertz represents cycles per second.
Radio waves are used not only for radio and TV, but also for remote controls, cell phones and radar.
The visible portion of the spectrum is the only region visible to people. We see it as the colors red, orange, yellow, green, blue, indigo and violet in order from long to short wavelength. Ultraviolet, X-rays and gamma rays are ionizing due to their high energy. This means they can remove electrons from atoms, including those that make up living tissues. Ionizing radiation contributes to cancer risk.