Flashcards
Electrical Surveying
Flashcards do conjunto (17)
- 1What are resistivity methods used for1.In the study of horizontal and vertical discontiuties in electrical properties of the ground.
2.To detect 3D bodies of anomalous electrical conductivity.
In shallow subsurface geology - 2Name two types of electrical methods1. Induced Polarisation (IP)
2.Self-potential - 3What type of current does electrical methods use and why?Usually direct currents but also low alternating currents to investigate electrical properties.
- 4what is measure in electrical surveyspotential difference
resistivity - 5Define ResistivityThe ability of a material to transmit electrical current that is independent of the geometrical factors.
- 6What is the equation used to calculate resistivityp(ohm-m)=RA/L
P= resistivity
R=resistance
L=length
A=cross section area - 7What is the reciprocal of resistivity?Conductivity measured in Siemens per metre(Sm-1)
- 8Where does current move in minerals that are insulators?Along the passage of ions in pore water.
- 9Define electrolytic.The flow of current by the movement of positive and negative ions.
- 10List major controls of resistivity in rcks1.Porosity (porosity decrease resistivity increases)
2. Crystalinity (rocks have interangular porosity so conductive along fissures and cracks.
3.Salinity - 11Can you identify rocks s solely by resistivIty dataNO!
- 12Define EquipotentialSurfaces of constant volatage
- 13State the equation for potential voltage at distance r .V=pl/2pie r
- 14Equation to calculate apparent resistivitypa= 2πa (ΔV/i)
- 15How do you increase depth of penetration in electrical surveying methodsBy increasing the separion space between the current electrodes
- 16Name two types of resistivity surveys procedures(VES) Vertical Electrical Sounding
(CST) Constant Separation Traversing - 17What is the CST used for1.To locate faults or shear zones
2.To determine variations in depth and find steep discontinuities.
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- FlashCards sobre Electrical Surveying, criado por Farie madondo em 06-04-2015.
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- Farie madondo
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