2 we also see that this beating dies out after t ∼ 4 μ s, leaving a sinusoidal oscillation at ν = ν 2. Hence, the shape of V ( t ) is due to a beating between two different frequencies. By taking the Fourier transform of the V ( t ) trace we observed two distinct frequency peaks at ν 1 = 1.95 MHz and ν 2 = 2.88 MHz, as shown in Fig. A short build-up time is followed by the expected exponential decrease, but the oscillation does not follow a perfect cosine. 2 the dots show an example of a V ( t ) trace obtained by measuring the voltage difference on the capacitor with the receiving antenna placed 1 m from the emitting antenna. We also had to insert the capacitors into a plastic bottle (a large soft drink) filled with oil to avoid dielectric breakdown in the air gap between the wires protruding from the capacitors.
#HEINRICH HERTZ CATHODE RAY EXPERIMENT SERIES#
The maximum voltage rating for the transformer is typically 15 kV or less, so that it is necessary to use at least two in series (and another two in parallel so as to maintain the same effective capacitance). We also used a 15 kV transformer, although in this case problems may arise with the capacitor. These waves may then be recaptured using a second loop antenna (RA) identical to the emitting antenna A, with a series capacitor with the same value as C. 4At each oscillation a large percentage of the power (of the order of 30%) will be lost due to emission from the loop antenna, that is, by the generation of propagating EM waves. The circuit will then start to oscillate at a frequency of ( 1 ∕ 2 π ) L C ∼ 2 MHz. The breakdown threshold in air is ∼ 3 kV ∕ mm, so that if the air gap is correctly adjusted, a spark will close the RLC circuit once a voltage difference of ∼ 6 kV is reached. As the voltage on the capacitor increases, the voltage also increases between the two extremities of the bolts. The 6 kV voltage supply oscillates at 50 Hz. The switch was constructed by taking two rounded bolts with a housing that lets us regulate the distance between the rounded extremities. An important part of the circuit is the spark-switch S inserted in one of the arms between the capacitor and the antenna. The circuit is powered by a 6 kV transformer T, which may be found from a neon-light dealer at low cost. The resistance of the circuit is provided directly by the circuit, for example, the antenna has R = 1.2 Ω. The inductance of the antenna L was measured with this setup and found to be roughly 5 μ H using different diameter tubing does not significantly change this value. A capacitance C of 1 nF ( 15 kV maximum voltage 3) is connected to a 1 m diameter loop antenna A obtained by bending a simple piece of copper tubing ( 1 in. The setup we used is a simple (RLC) circuit (see Fig. Among these are a clear demonstration of power transmission, a precise characterization of loop antenna emission, the observation of frequency splitting due to resonator coupling, and the near-field decay of the electric and magnetic fields created by a loop antenna. The purpose of this paper is to describe an experimental setup that is a modification of the original setup and yields insight and direct measurements of many aspects related to EM emission. Notwithstanding the importance and impact of these experiments it is uncommon to find these experiments reproduced in some form or another. In the same group of experiments Hertz also observed for the first time many other effects, most notably the photoelectric effect.
#HEINRICH HERTZ CATHODE RAY EXPERIMENT FREE#
1,2 In particular, he showed that it is possible to generate electromagnetic (EM) waves that propagate in free space with a well defined frequency and wavelength, it is possible to observe interference between these waves, and most importantly, that these waves transport energy. Heinrich Hertz is best known for his series of experiments conducted from 1886 onward with which he demonstrated that the predictions of Maxwell were correct.
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