There are seven types of electromagnetic radiation. The electromagnetic spectrum organizes them by wavelength and frequency. The top of a wave
is called the crest. Wavelength is the distance from the crest of one wave to
the crest of the next. This distance can be as big as a football field or as
small as an atom's nucleus. Wavelength is typically measured in meters or
nanometers (inm = 0.0000000001m). Frequency is the number of times a
crest occurs per second. The unit of measurement for frequency is Hertz (1
Hz = one cycle per second). There is an inverse relationship between
wavelength and frequency. That means, types of waves with longer
wavelengths have lower frequencies. Shorter wavelengths have higher
frequencies. The order of waves in the spectrum is as follows: radio waves,
microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays.
Each type of wave has important uses and some risks.
According to this passage, the seven different types of electromagnetic radiation
A are useless and harmless.
B
have the same frequencies.
have different wavelengths.
are organized on separate spectrums.