PROPAGATION OF TRANSIENT ELECTROMAGNETIC WAVES IN A MEDIUM OF FINITE CONDUCTIVITY

Geophysics ◽  
1957 ◽  
Vol 22 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Bimal Krishna Bhattacharyya
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Rise Time ◽  
Electromagnetic Waves ◽  
Input Pulse ◽  
Dipole Source ◽  
Finite Conductivity ◽  
Transient Electromagnetic ◽  
Electric And Magnetic Fields ◽  
Ramp Function

Transient electric and magnetic fields have been calculated for ramp function and sawtooth current sources immersed in a semi‐conducting medium. An electric dipole source has been assumed. In the case of ramp function input, it is observed that the peaks of the overshoots in the θ‐component of the electric field decrease in magnitude with the increase in rise time of the input pulse. It has also been shown that the rise time of the current pulses has definite effect upon the rise time and amplitude of the electric fields and that the sawtooth exciting pulses having large values of rise time may be conveniently used to obtain measurable values of the electric and magnetic fields.

Discussions and Communications: Propagation of Transient Electromagnetic Waves in a Conducting Medium

Geophysics ◽  
1955 ◽  
Vol 20 (4) ◽  
pp. 959-961 ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electromagnetic Waves ◽  
Step Function ◽  
Conducting Medium ◽  
Initial Value ◽  
Transient Electromagnetic ◽  
Ramp Function

Wait (1951) has calculated the transient electric fields for several types of step-function current sources placed inside a conducting medium. Now any generated pulse will require a finite build-up time to reach its final magnitude from its initial value of zero. In most cases, this type of pulse may be very well approximated by a ramp-function pulse (Figure 1). Expressions for the electric field of this type of pulse will be deduced in the following analysis.

scholarly journals The basic theory of bipolars existence and their role in the examination of electric and magnetic fields

2021 ◽  
Vol 34 (3) ◽  
pp. 315-321
Author(s):  
Farzad Haghmoradi-Kermanshahi
Keyword(s):  
Magnetic Fields ◽  
Electromagnetic Waves ◽  
Fine Particles ◽  
Basic Theory ◽  
Electrical Charge ◽  
Negative Pole ◽  
Electric And Magnetic Fields ◽  
Physical Phenomena ◽  
The Universe

This article claims that the universe is composed of very fine particles, which are billions of times smaller than electrons. These particles consist of one positive pole and one negative pole similar to protons and electrons (in terms of electrical charge), respectively. They are point electric charges, which their movements and bending of their chain in space create magnetic fields and electromagnetic waves. These particles possess mass that verges on zero, due to their minute size. Then, by examining several physical phenomena, the presence of them will be proved.

A time‐domain EM system measuring the step response of the ground

Geophysics ◽  
1984 ◽  
Vol 49 (7) ◽  
pp. 1010-1026 ◽  
Author(s):  
G. F. West ◽  
J. C. Macnae ◽  
Y. Lamontagne
Keyword(s):  
Magnetic Fields ◽  
Impulse Response ◽  
Electric Fields ◽  
Time Domain ◽  
Wide Band ◽  
Step Response ◽  
System Function ◽  
Response Measurement ◽  
Resistivity Method ◽  
Electric And Magnetic Fields

A wide‐band time‐domain EM system, known as UTEM, which uses a large fixed transmitter and a moving receiver has been developed and used extensively in a variety of geologic environments. The essential characteristics that distinguish it from other systems are that its system function closely approximates a stepfunction response measurement and that it can measure both electric and magnetic fields. Measurement of step rather than impulse response simplifies interpretation of data amplitudes, and improves the detection of good conductors in the presence of poorer ones. Measurement of electric fields provides information about lateral conductivity contrasts somewhat similar to that obtained by the gradient array resistivity method.

Effect of a Conducting Overburden on the Fields of a Buried Dipole Source

1975 ◽  
Vol 53 (6) ◽  
pp. 598-609 ◽  
Author(s):  
V. Ramaswamy ◽  
H. W. Dosso
Keyword(s):  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Analytical Solutions ◽  
Electric Dipole ◽  
Lower Layer ◽  
Low Frequency ◽  
Dipole Source ◽  
Vertical Electric Dipole ◽  
Electric And Magnetic Fields ◽  
Horizontal Electric Dipole

Analytical solutions for the low frequency electromagnetic fields of a dipole source situated in the lower layer of a two layer conductor are derived. The sources considered are a vertical electric dipole, a horizontal electric dipole, and a horizontal magnetic dipole. The numerical results discussed in this paper describe the general behavior of the electric and magnetic fields for various upper layer conductivities, upper layer thickness, and source depths. The results are of interest in the application of electromagnetic techniques to locate miners trapped underground following a mine disaster.

Hall Currents and the Ejection of Prominences by Sunspots

1949 ◽  
Vol 2 (1) ◽  
pp. 39
Author(s):  
RG Giovanelli
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Magnetic Force ◽  
Large Space ◽  
Space Charges ◽  
Surrounding Atmosphere ◽  
Electric And Magnetic Fields ◽  
Order Of Magnitude ◽  
General Movement ◽  
Set Up

During the growth of sunspots induced electric fields may be expected to be set up in the surrounding atmosphere. It is shown that, because of the comparatively low conductivity perpendicular to lines of magnetic force, there are localized regions where large space charges occur, resulting in large electric fields perpendicular to the lines of magnetic force. Consequently both positive and negative charges drift in the same sense in a direction which is at right angles to the electric and magnetic fields, giving rise to a general movement of the gas. The drift velocities are difficult to estimate, but appear to be of the order of magnitude of those found in eruptive prominences.

Elastic Constants of Nematic Liquid Crystals

1972 ◽  
Vol 27 (6) ◽  
pp. 966-976 ◽  
Author(s):  
Hans Gruler ◽  
Terry J. Scheffer ◽  
Gerhard Meier
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Detailed Comparison ◽  
Theoretical Treatment ◽  
Electrical Capacitance ◽  
Normal Deformation ◽  
Electric And Magnetic Fields ◽  
The Magnetic Field ◽  
Dynamic Phenomena ◽  
Good Agreement

Abstract We present a theoretical treatment and give experimental observations of the deformation that occurs in a nematic liquid crystal when electric or magnetic fields are applied. We consider only normal deformations in the nematic material where fluid flow and other dynamic phenomena play no role. Three important sample geometries are considered in the magnetic field, and the experimentally observed deformations are in good agreement with theory. The normal deformation induced by electric fields is of interest from a device standpoint, and we give a solution for the deformation that is valid even for large dielectric anisotropics. This solution has been experimentally verified. We give a detailed comparison of the distortions produced by electric and magnetic fields and show that the deformations are of a similar form even though the field is nonuniform in the electric case. The change in birefringence and electrical capacitance as a function of distortion is discussed as a means of observing the deformation.

scholarly journals Влияние магнитных и электрических полей на динамику образования плазмоидов в гатчинском разряде

2022 ◽  
Vol 92 (3) ◽  
pp. 366
Author(s):  
Shixin Zhao ◽  
Chengxun Yuan ◽  
А.А. Кудрявцев ◽  
Jingfeng Yao ◽  
Г.Д. Шабанов
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Electric Charge ◽  
Active Phase ◽  
Ball Lightning ◽  
Electric And Magnetic Fields ◽  
Direction Of Movement

The behavior in magnetic and electric fields of the Gatchina discharge, which is used mainly to create an analog of ball lightning in the laboratory in a normal atmosphere, is analyzed. Shown that in these studies it is possible to determine the sign of an uncompensated electric charge as in the active phase of the discharge, and in the forming long-lived luminous formations. Also shown that electric and magnetic fields can change the direction of movement of the forming luminous formation and even completely block its formation. The type and mechanism of existence firework ball lightning are considered, photos of which are presented in widely known monographs on the ball lightning.

Reply to J. R. Wait by D. Rankin and R. P. Singh

Geophysics ◽  
1984 ◽  
Vol 49 (8) ◽  
pp. 1388-1388
Author(s):  
D. Rankin ◽  
R. P. Singh
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Horizontal Surface ◽  
Electric And Magnetic Fields ◽  
Surface Measurements

There is no real dispute between the magnetotellurist (Cagniard school) and the radio physicist (Norton school) in surface measurements of VLF and ULF fields. Each defines a mutually exclusive quantity which requires a different mode of measurement. The magnetotellurist measures the horizontal surface electric and magnetic fields, whereas, as Wait correctly points out, the radio physicist measures the horizontal and vertical electric fields.

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