Electromagnetic Waves
From WikiEducator
| Electromagnetic (EM) waves are transverse waves composed of a sinusoidal electric field oscillation and a sinusoidal magnetic field oscillation. The magnetic and electric field oscillations are in phase (when one is has a maximum displacement so does the other). The magnetic field oscillates perpendicular (90°) to the electric field oscillation. The magnetic field and electric field both oscillate perpendicular to the direction the wave travels. EM waves do not require a medium to propagate and they carry their own momentum. All EM waves travel at the speed of light in a vacuum. |
| Polarisation is a property of EM waves (and all transverse waves) that describes the orientation of the displacement perpendicular to the direction of travel. For an EM wave this orientation is typically discussed in terms of the electric field. |
electromagnetic waves are formed by vibration of an electric charge
- a slower vibration creates a wave with a longer wavelength and a low energy
- a faster vibration creates a wave with a shorter wavelength and a high energy
eg. radio waves (longer wavelength)
microwaves
infra-red waves
Visible light waves (ROYGBIV)
Ultra violet waves
- X-rays
- Gamma rays (shorter wavelength)
Contents
Electromagnetic Spectrum
| Click the show/hide link to view the EM spectrum graphic |
|---|
| http://upload.wikimedia.org/wikipedia/commons/8/8a/Electromagnetic-Spectrum.png |
Gamma rays
Wavelength Range
Gamma Rays have the shortest coil wavelength, below about 10 picometers
X-rays
The first X-ray! http://upload.wikimedia.org/wikipedia/en/thumb/6/6e/Anna_Berthe_Roentgen.gif/180px-Anna_Berthe_Roentgen.gif
Wavelength Range
X-Rays have a wavelength in the range of 10 to 0.01 nanometers
Ultra violet
Skin Cancer, sun burns
