| Source of em radiation | Generation process | wavelength(m) |
|---|---|---|
| 60 Hz power line | oscillating electrical current | 5.00 x 106 |
| TV/FM radio | oscillating electrical current | 3.15 |
| cell phone (900MHz) | oscillating electrical current | 3.33 x 10-1 |
| infrared from hot object |
thermal motion of charged particles (usually electrons) | 5.00 x 10-6 |
| red light (Halpha Balmer) | n=3 to n=2 electron transitions from ionized hydrogen | 6.56 x 10-7 |
| visible (violet) | energy lost from free (continuum) electrons | 4.00 x 10-7 |
| solar ultraviolet A |
energy lost from free (continuum) electrons | 3.60 x 10-7 |
| solar ultraviolet B |
energy lost from free (continuum) electrons | 3.00 x 10-7 |
| solar ultraviolet C |
energy lost from free (continuum) electrons | 2.75 x 10-7 |
| ultraviolet (Lalpha Lyman) atoms | n=2 to n=1 electron transitions from ionized hydrogen | 1.21 x 10-7 |
| soft X-rays | sudden deceleration of electrons by colliding them into a metal plate | 2.00 x 10-9 |
| hard X-rays | the collision of very high speed electrons with a metal plate | 1.00 x 10-13 |
| low energy gamma ray | radioactive decay | 1.00 x 10-13 |
| high energy gamma ray | unidentified high energy astrophysical processes | 1.00 x 10-21 |