MYP Physics Electromagnetic Spectrum, Imaging and Applications Notes

The Electromagnetic Spectrum Organizes All Types Of "Light"

1. Light is only a small part of a much bigger family of waves.
2. The electromagnetic spectrum is the continuous range of all electromagnetic (EM) waves, from extremely long wavelengths (radio) to extremely short wavelengths (gamma rays).
3. Even when we cannot see a wave, it still exists and can be useful.
4. A key feature of EM waves is that, in a vacuum, they all travel at the same speed, the speed of light: $$c = 3.0 \times 10^8 \text{ m s}^{-1}$$
5. They are also all transverse waves, meaning the oscillations are perpendicular to the direction the wave travels.

Wavelength, Frequency, And Energy Are Linked

1. Electromagnetic waves are described using measurable wave quantities.
2. Wavelength is the distance between two corresponding points on a wave.
3. Frequency is the number of wave cycles passing a point each second.
4. For electromagnetic waves in a vacuum:
   1. Speed is constant
   2. Wavelength and frequency are inversely related
5. For any wave, $$c = f\lambda$$
6. So if $c$ is fixed (as it is for EM waves in a vacuum), then shorter $\lambda$ implies larger $f$, and longer $\lambda$ implies smaller $f$.

Order of the Electromagnetic Spectrum

1. The spectrum is ordered systematically.
2. From longest wavelength / lowest frequency to shortest wavelength / highest frequency:
   1. Radio waves
   2. Microwaves
   3. Infrared
   4. Visible light
   5. Ultraviolet
   6. X-rays
   7. Gamma rays
3. As you move along the spectrum:
   1. Wavelength decreases
   2. Frequency increases
   3. Energy carried by the wave increases

Visible Light Is A Small Window (400–700 nm)

1. Visible light is a small but important part of the spectrum.
2. Visible light is the only part of the electromagnetic spectrum that the human eye can detect.
3. It has wavelengths approximately between 400 nm (violet) and 700 nm (red).