#1 EM Spectrum Notes by phydotsi


									Electromagnetic (EM) Spectrum
EM waves transfer energy from one place to another. They do not transfer matter (think about a
wave on a slinky). There are many different type of EM wave, each with different properties. These
different properties are determined by their different wavelengths.

All EM waves travel at the same speed, c, the speed of light, or 3 × 108 m/s.

The wavelength, λ (“lambda”, in metres, m), frequency, f (in Hertz, Hz ) and speed, c (in metres per
second, m/s), are linked by this equation:

                                               c = fλ

We know that c remains constant – all EM waves travel at the same speed. So, as wavelength increases
the frequency must decrease. λ ↑ ⇒ f ↓.

We have mentioned wavelength, but what is it? All EM waves are transverse waves, meaning they
oscillate from side to side or up and down. The wavelength is the length between two peaks (high
points) or between two troughs (low points):

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