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The radiation will be appreciable only if the amplitude of oscillation of charge is comparable to the wavelength of radiation that it emits. This rules out mechanical vibration, for assuming a vibrational frequency of 1000 cycles per second, the wavelength work out to be 300 km. Hertz, therefore, made the oscillating charges vibrate with a very high frequency. The apparatus consists of two brass plates connected to the terminals of a secondary of a transformer. The primary consists of an LC oscillator circuit, which establishes charge oscillations at a frequency of  . As the primary circuit oscillates, oscillations are set up in the secondary circuit. As a result, rapidly varying alternating potential difference is developed across the gap and electromagnetic waves are generated. Hertz was able to produce waves having wavelength of 6m. It was soon realized that irrespective of their wavelength, all electromagnetic waves travel through empty space with the same speed, viz., the speed of light. |
