List of top Geology and Geophysics Questions on Electromagnetics

A primary electromagnetic field (\( H_P \)) is being generated from current \( I_P \) flowing in a coil A with negligible capacitance, such that \( H_P = K I_P \sin \omega t \), where \( \omega \) is the angular frequency, \( K \) is a constant and \( t \) is time. A secondary electromagnetic field is being produced by induction in a conducting coil B. The phase difference between the primary and the secondary electromagnetic fields depends on which of the following factors?
A loop of radius \( R \) carries a current \( I \) and produces a magnetic field \( B \). Which of the following statements is/are correct about \( B \)?
Given the following electric field in Cartesian coordinates: \[ \mathbf{E} = x^2 y \hat{i} + y^2 z \hat{j} + z^2 x \hat{k}, \] which of the following statements is/are correct?
Which one of these statements is NOT correct for electromagnetic waves travelling through the subsurface?
The amplitude of a monochromatic 1000 Hz EM wave reduces by a factor of \(1/e\) after penetrating to a depth of 100 m in a homogeneous medium. Given the magnetic permeability of free space \(\mu_0 = 4\pi \times 10^{-7}\,\text{H/m}\), the electrical conductivity of the medium in S/m is _________ (rounded off to three decimal places).
A Wenner resistivity survey was performed with a spacing of 15 m between the current electrodes. Potential difference values of \(-25\ \text{mV}\) and \(225\ \text{mV}\) were measured before and after injecting \(100\ \text{mA}\) current into the ground. The apparent resistivity in \(\Omega\cdot\text{m}\) after correcting for the self-potential effect is:
A current of 2 A passes through a cylindrical rod with uniform cross-sectional area of 4 m$^2$ and resistivity of 100 $\Omega$-m. The magnitude of the electric field (E) measured along the length of the rod in V/m is _________ (in integer).
The CORRECT sequence(s) of electromagnetic radiations in terms of increasing wavelength is/are:
A rock is fully saturated with water of resistivity \(\rho_w=0.25\ \Omega\text{m}\). The bulk resistivity is \(\rho=60\ \Omega\text{m}\). Using Archie's law with \(a=1\) (tortuosity factor) and \(m=2\) (cementation exponent), determine the porosity \(\phi\) in percent. \([\,\text{round off to 2 decimals}\,]\)