| 2. Electric dipole radiation (contd..) |
| Electric dipole radiation: salient features |
- The radiated power is proportional to the fourth power of
frequency. This results in the blue colour of the sky: the sunlight
induces dipoles in the air molecules, which then radiate, giving
out more light at high frequencies, i.e. near the blue end of the
spectrum.
|
- The angular dependance is
 , i.e. there is no radiation in the
direction of the dipole, most of the radiation is in the equatorial
plane.
|
- At large wavelengths
 antennas (discussed in the last
lecture) also emit dipole radiation.
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