EMI Flashcards
What is Gauss’s Law
total electric field flux through a closed surface is equal to the contained electric charge
What is Ampere’s Law
an electrical current generates a magnetic field
What is Faraday’s Law
magnetic field variations induce an electric field in a conductor.
What parameters control the behaviour of an electromagnetic wave in a non-magnetic earth
The frequency of the electromagnetic signal, electrical conductivity and the dielectric permittivity of the Earth material.
What is skin depth
The exponential decay constant d gives us a measure of the rate at which the magnitude of the EM field decreases with propagation depth in the Earth
The parameter d defined by (1/μσπf)1/2 is called the skin depth.
What are the EMI steps
- Alternating current is passed through Tx loop
- primary time varying field is generated
- primary field induces eddy currents
- eddy currents generate time varying field
- secondary field is detected
Describe Frequency-Domain Electromagnetic (FDEM) Methods
the Tx coil emits a continuous sinusoidal primary magnetic field at a given cyclic frequency f
Describe Time-Domain Electromagnetic (TDEM) Methods
TDEM works by switching off the primary field and measuring the secondary field in its absence.
