DOI:10.1049/jiee-1.1926.0064

出版商:IEE    

年代:1926

数据来源: IET

摘要:

Methods are given of computing to any desired accuracy the capacity of a spherical condenser when the bounding spherical surfaces are not concentric. Methods of calculating the attraction on the inner sphere and the maximum potential gradient in the field between the two shells are given. The results obtained are of use in calculating the capacity coefficients of spherical electrodes. They are directly useful also when measuring by standard methods the inductivity (specific inductive capacity), the thermal conductivity and the electrical conductivity of homogeneous substances.

DOI:10.1049/jiee-1.1926.0065

出版商:IEE    

年代:1926

数据来源: IET

摘要:

This paper describes an apparatus which has been developed for observing, by a direct deflection method, small changes in the effective resistance and inductance of a coil. It consists of a bridge network, with two inductive arms, which is normally balanced. The bridge is supplied with alternating currents, the indicating instrument being a d.c. galvanometer connected through a synchronously driven commutator. One of the arms of the bridge contains the “exploring“ coil, which is placed on the metal surface to be examined. It is shown that if the commutator is so adjusted as to indicate the current in phase with the applied voltage, its deflection is proportional to the change in effective resistance of the exploring coil. With the commutator adjusted to observe currents 90° out of phase with the applied voltage, the deflection depends on the change in effective inductance of the coil, when this change is brought about by the presence of a metal plate. For non-magnetic materials it is best to use the commutator in the “out of phase” position. The change in effective inductance depends on the specific conductivity of the plate, and the apparatus may be used for quickly comparing the specific conductivities of metal plates. If such plates have cracks normal to the surface, their presence is indicated by a reduction in the galvanometer deflection as the coil passes over a crack. For magnetic materials the commutator should be set in the “in phase” position. Cracks in magnetic materials can be observed in the same way as those in nonmagnetic materials.

DOI:10.1049/jiee-1.1926.0066

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper describes a method for generating magnetic fields of the order of magnitude of 1 million gauss, and for impressing such fields on a specimen of magnetic material at regular intervals, with a view to ascertaining whether any disturbance of the electronic orbits could be obtained of sufficient magnitude to produce a marked effect on the magnetization curve of the specimen.An account is given of the means used for measuring the magnitude and frequency of the heavy transient currents to which the intense magnetic fields are due.The influence of the dimensions of the solenoid through which the transient currents flow is considered as determining the intensity of the magnetic field produced.A comparison is given of the calculated and measured values of the transient currents for three different solenoids. It is found that, whilst the calculated values agree well with the measured values for solenoids with a relatively small number of turns of thick wire, there is an appreciable discrepancy in the case of a solenoid with a large number of turns of thin wire. An attempt is made to explain this discrepancy as due to the condenser effect of the contact E.M.F. between the copper wire and the oil-soaked cotton insulation which is in contact with the wire.

DOI:10.1049/jiee-1.1926.0067

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper consists of the statement and illustration of a method of solving recurrent circuits (of which the filter is the simplest example) when operating in the “steady-state” condition, by reducing each element to a “rejector” resonant at the operating frequency.The method is stated and is illustrated by the “low-pass” and “high-pass” filters. The general case of a filter is solved. Characteristics of the simpler types of filters are stated briefly.The initial sending-end impedancs of the line and the condition for non-reflection are written down from inspection. It is shown that, for one-way working, it is not necessary, or desirable (as is often stated), that the transmitter, receiver, and initial sending-end impedances should all be equal.Line distortion due to reflection is considered briefly.A worked example is given in the Appendix.Although the method is applied here to niters only, it is readily extended to both continuous and loaded lines.

DOI:10.1049/jiee-1.1926.0068

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper calls attention to the present condition of knowledge on the subject of the attenuation of wireless waves travelling over the earth's surface, due to energy absorption by the earth itself. The theories put forward on this problem by Sommerfeld and Zenneck are briefly outlined, and it is shown that the latter has taken account only of a special case of the more general theory of Sommerfeld. The results deduced from this theory have been worked out for some typical practical cases of both short- and long wave transmission, but, owing to the complete lack of experimental evidence, no practical test of the theory has yet been made. In view of the importance of a knowledge of ground absorption in connection with the complete study of the propagation of wireless waves of all lengths over the earth's surface, it is highly desirable that a systematic experimental investigation should be carried out in the near future.

DOI:10.1049/jiee-1.1926.0069

出版商:IEE    

年代:1926

数据来源: IET

DOI:10.1049/jiee-1.1926.0077

出版商:IEE    

年代:1926

数据来源: IET