On: “On the Effects of Overburden on EM Anomalies—A Review” by Amalendu Roy (GEOPHYSICS, August 1970, p. 646–659)

Geophysics ◽  
1971 ◽  
Vol 36 (1) ◽  
pp. 216-217
Author(s):  
James R. Wait
Keyword(s):  
Electromagnetic Response ◽  
Conducting Sphere ◽  
Screening Factor

In a grossly inaccurate discussion, Roy (1970) criticizes my analysis of screening factors for the electromagnetic response of a conducting sphere (Wait, 1969). The screening factor [Formula: see text] was clearly defined in my paper as the ratio of two specified quantities.

Electromagnetic response of a permeable inhomogeneous conducting sphere

1973 ◽  
Vol 11 (1-3) ◽  
pp. 1-20 ◽  
Author(s):  
Janardan G. Negi ◽  
Chandra P. Gupta ◽  
Upendra Raval
Keyword(s):  
Electromagnetic Response ◽  
Conducting Sphere

NEGATIVE ELECTROMAGNETIC SCREENING BY A CYLINDRICAL CONDUCTING COVER

Geophysics ◽  
1969 ◽  
Vol 34 (6) ◽  
pp. 944-957 ◽  
Author(s):  
Janardan G. Negi ◽  
Upendra Raval
Keyword(s):  
Numerical Evaluation ◽  
Inner Core ◽  
Electromagnetic Response ◽  
Spherical Case ◽  
Cylindrical Model ◽  
Cylindrical System ◽  
Screening Factor ◽  
Analytical Expressions ◽  
Electromagnetic Screening

The paradoxical augmentation of the electromagnetic response of an inner core by a conducting cover is reexamined by investigating the behavior of a cylindrical model to establish the geometrical independence of the negative screening phenomenon. The theory is developed for the coaxial cylindrical system in analogy with the spherical case. Results of numerical evaluation of the analytical expressions for the screening factor prove the geometrical independence of the phenomenon of negative screening, as indicated in earlier studies.

ELECTROMAGNETIC INDUCTION IN A SOLID CONDUCTING SPHERE ENCLOSED BY A THIN CONDUCTING SPHERICAL SHELL

Geophysics ◽  
1969 ◽  
Vol 34 (5) ◽  
pp. 753-759 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Spherical Shell ◽  
Electromagnetic Induction ◽  
The Other ◽  
Electromagnetic Response ◽  
Core Radius ◽  
Homogeneous Sphere ◽  
Conducting Sphere ◽  
The Core ◽  
Quadrature Phase ◽  
Dipole Response

By means of a straightforward boundary‐value treatment, a solution is obtained for the electromagnetic response of a homogeneous sphere enclosed by a uniform spherical shell. A quasi‐static assumption is invoked at the outset because attention is directed to slowly varying fields. Expressions are derived for the “in‐phase” and “quadrature phase” response of the induced multipoles. These are a function of the radius, conductivity, and permeability of the core, and the radius, conductivity, and thickness of the shell. Some numerical results for the nonpermeable case indicate that the dependence of the dipole response on the normalized core radius is altered significantly by the presence of the shell. On the other hand, the ability to detect the presence of the core is not greatly impaired.

scholarly journals Electromagnetic response of a conducting sphere buried in a conducting earth.

1974 ◽  
Vol 26 (4) ◽  
pp. 417-427 ◽  
Author(s):  
S. O. OGUNADE ◽  
V. RAMASWAMY ◽  
H. W. DOSSO
Keyword(s):  
Electromagnetic Response ◽  
Conducting Sphere

DIFFRACTION OF ELECTROMAGNETIC WAVES BY AN INHOMOGENEOUS SPHERE

Geophysics ◽  
1962 ◽  
Vol 27 (4) ◽  
pp. 480-492 ◽  
Author(s):  
Janardan G. Negi
Keyword(s):  
Half Space ◽  
Electromagnetic Waves ◽  
Homogeneous Medium ◽  
Electromagnetic Response ◽  
General Situation ◽  
Conductivity Distribution ◽  
Conducting Sphere ◽  
Conductivity Variation ◽  
Magnetic Contrast ◽  
Inhomogeneous Sphere

The electromagnetic response of an inhomogeneous conducting sphere (having radial conductivity distribution) embedded in an infinite homogeneous medium is investigated. The effect of linear conductivity variation and magnetic contrast between the two media is discussed in detail and relevant curves are presented. Analytical results are further extended to a more general situation in which this sphere is located in a half‐space and the influence of air‐earth boundary is calculated. These results may be applied to geoelectrical interpretation.

ON THE ELECTROMAGNETIC RESPONSE OF A CONDUCTING SPHERE TO A DIPOLE FIELD

Geophysics ◽  
1960 ◽  
Vol 25 (3) ◽  
pp. 649-658 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Magnetic Dipole ◽  
Electromagnetic Coupling ◽  
Wave Length ◽  
Dipole Field ◽  
Electromagnetic Response ◽  
Geophysical Prospecting ◽  
End Points ◽  
Conducting Sphere ◽  
Ore Body ◽  
Set Up

The electromagnetic coupling between an electric and a magnetic dipole in the presence of a spherical ore body is discussed in the present paper. It is shown that both electric and magnetic modes must be considered even though all dimensions are small compared to the wave length. The results have application to a geophysical prospecting scheme where the exciting fields are set up by a straight insulating wire grounded at its end points and the secondary fields are detected by an ungrounded closed wire loop.

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