V.3 No 1

77

Several experiments studying dynamic magnetic field

2.3. Results of experimental study

The results of experimental study are shown in the Table 1, and plots U₂₁ (f), U₂₂ (f), ₂₁ (f), (f) are shown in Figures 6 - 8.

Table 1

Fig. 6. The amplitude of induced emf in the interior (red curve) and exterior (green curve) windings of the air-core transformer against the frequency of current in the primary winding

Fig. 7. The phase shift of induced emf in the interior winding of the air-core transformer relatively the voltage phase in the primary winding, against the frequency of current in the primary winding equal to 2 V (red curve) and 4 V (green curve)

Fig. 8. The phase shift between the induced voltages across the interior and exterior windings against the frequency of current in the primary winding, at the voltage across the primary winding equal to 2 V (blue curve) and 4 V (green curve)

Analysing the obtained experimental results, we can make two conclusions:

1. Within the entire frequency range, the phase difference between the induced emfs in the interior and exterior windings is practically zero. This evidences of one direction of vector   for both windings. Thus, as opposite to the conventional concept of phenomenology of process of induction, the dynamic magnetic field basically cannot be closed, since in this case we would see in this experiment the phase shift equal to 180 degrees. And in the low-frequency range, where Purcell saw the most full agreement between the theory and experiment, the phase difference of induced emf between the interior and exterior secondary windings is exactly zero (at least with all rigour of observability in the experiment).
2. In the plot ₂₁ (f) in Fig. 7 we can see that the phase shift between the voltages across the primary and secondary windings is inconstant and decreases with the frequency. At the frequency higher than 2 10⁴ Hz, with the present parameters of experimental device, the phase changes its sign. At the same time we register the appeared difference between the phases of emfs induced in the interior and exterior windings. The difference in phases of induced emfs is caused by some difference of the inductance of secondary windings which appears considerable at high frequencies. Furthermore, the yielded results evidence, at the above frequencies there reveal the resonance properties of inductances of secondary windings that create the resonance loops with the parasitic capacitances of these windings.

On the whole, the presented set of experiments has corroborated correct the conclusions that the lines of force of dynamic magnetic field are open, as we proved it theoretically in [1]. At the same time, this experimental circuit did not lift all questions - particularly, of the phenomenology of the very process, how the energy is transmitted from the primary loop to secondary. This required to carry out a deeper study of dynamic magnetic field.