SELF

88

S.B. Karavashkin and O.N. Karavashkina

Before we analyse the data of Table 3, we have to mark the low accuracy of emf values yielded in subtraction, because the value of emf induced in the inner side of loop well exceeds that induced in the outer side. For example, at h = 0 cm and  f = 200 kHz, the table 3 gives U = 0, 275  V , and the table 2 for h = 18 cm  and  f = 200 kHz gives  U = 2, 4 ? . Thus, the ratio of emf induced in the outer side of secondary loop to that induced in the inner side is 0,115 - only 10 %. As both values were measured accurate to dimension of numbers shown in Table 2, in subtraction the error grows in proportion to the decrease of difference, i.e. in 8,73 times. So the diagram plotted after the values presented in Table 3 can be considered only as a qualitative pattern of regularity. The smoothed plot of induction emf in the outer side of loop with respect to f and h is shown in Fig. 16.

Fig. 16. Induction emf in the outer side of loop with respect to the frequency f of current in the primary winding and to the distance h from this side to the core

Despite the indicated limitation in accuracy of results for the outer side of secondary loop, we see that the values of emf presented in Table 3 coincide, in limits of error, with the values of Table 1. At the same time, the emf variation in all the studied range lower than 80 kHz, which is presented in Fig. 16, corresponds to the results obtained in the first experiment and shown in Fig. 11. In both cases, with the loop size distanced from the core the emf monotonously falls, which is fully opposite to the Maxwell formulation and fully corresponds to the Faraday definition of induction.

Thus, both in the first and second experiment, the emf of induction is excited not in the secondary loop as the whole but in its definite parts, and in each part the amplitude of emf is proportional not to the total flux through the secondary loop, but to the value of magnetic field strength at the location of loop wire. In particular, this explains the unequal value of emf inducing in the inner and outer wires of secondary loop in the second experiment. As the inner wire of secondary loop is surrounded by the core, the induced emf will be proportional to the sum of emf induced by the whole surface of core. While for the outer wire the emf is induced only by the outer side of core, whose field is not concentrated, as in the window of transformer core, but is scattered, whereupon the inhomogeneous field, which we measured in the first experiment, is formed. Should we measure the field in the window of core, we would obtain practically equal values in the whole cross-section. Only in the corners of window the emf would negligibly grow on the inhomogeneities of core.

The obtained theoretical and experimental results fully corroborate that we legally used in [1] the compensative loop to measure the induction emf induced in the single rod. With quite large distance from tapping sides of loop and with low frequency of inducing field, the emf induced in these sides will be practically zero. We should mark, with the same result we can use single loops instead those compensative, if keeping a considerable distance of idle sides of loop from the studied core.