12.7: Antenna Systems (Summary)
- Page ID
- 103513
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Key Terms
| transverse wave | a wave, such as an electromagnetic wave, which oscillates perpendicular to the axis along the line of travel |
| standing wave | a wave that oscillates in place, with nodes where no motion happens |
| wavelength | the distance from one peak to the next in a wave |
| amplitude | the height, or magnitude, of an electromagnetic wave |
| frequency | the number of complete wave cycles (up-down-up) passing a given point within one second (cycles/second) |
| resonant system | a system that displays enhanced oscillation when subjected to a periodic disturbance of the same frequency as its natural frequency |
| oscillate | to fluctuate back and forth in a steady beat |
Summary
Production of Electromagnetic Waves
- Electromagnetic waves are created by oscillating charges (which radiate whenever accelerated) and have the same frequency as the oscillation.
- Since the electric and magnetic fields in most electromagnetic waves are perpendicular to the direction in which the wave moves, it is ordinarily a transverse wave.
- The strengths of the electric and magnetic parts of the wave are related by \[\frac{E}{B} = c, \nonumber\] which implies that the magnetic field \(B\) is very weak relative to the electric field \(E\).