Gravity & Magnetic Surveying

20 Questions | Total Attempts: 2029

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Gravity & Magnetic Surveying

This Quiz contains the questions from the basics and applications of Gravity and Magnetic methods used in Geophysical Investigations. Enjoy the Quiz n Tk cr. . . . . Be Happy. . . All the best. . . . .


Questions and Answers
  • 1. 
    Gravity field variations on the surface :
    • A. 

      Reflects the density variation laterally in the subsurface

    • B. 

      Reflects the density variation vertically in the subsurface

    • C. 

      Do not reflect density variation

    • D. 

      Reflect topogrphic variations only

  • 2. 
    Sensitivity of a Gravimeter is :
    • A. 

      0.01 mgal

    • B. 

      0.1 mgal

    • C. 

      0.002 mgal

    • D. 

      0.001 mgal

  • 3. 
    Optical Pumping magnetometer works on the pinciple of:
    • A. 

      Doppler effect

    • B. 

      Proton Precession

    • C. 

      Magnetic saturation

    • D. 

      Zeeman effect

  • 4. 
    The half width of vertical magnetic intensity anomaly over a magnetised sphere is 25 meters .  Calculate the depth to the center of sphere from surface ??
    • A. 

      32.5 m

    • B. 

      50 m

    • C. 

      25 m

    • D. 

      None of these

  • 5. 
    Van allen zones form at :
    • A. 

      North Pole

    • B. 

      South Pole

    • C. 

      North and South both

    • D. 

      Equator

  • 6. 
    The scale of Geodetic Survey is :
    • A. 

      1:250000

    • B. 

      1:10000

    • C. 

      1:5000

    • D. 

      1:50000

  • 7. 
    At magnetic equator, the inclination of total magnetic field is :
    • A. 

      90 degree

    • B. 

      60 degree

    • C. 

      45 degree

    • D. 

      0 degree

  • 8. 
    A gravity profile across a schist belt within a Granitic country rock will give rise to a :
    • A. 

      Central low

    • B. 

      Central High

    • C. 

      Response is flat

    • D. 

      High and Low at the edges

  • 9. 
    Which of the following is non-magnetic ???
    • A. 

      Granite

    • B. 

      Gabbro

    • C. 

      Limestone

    • D. 

      Diorite

  • 10. 
    A large sedimenary basin 2 km deep with density contrast of 0.3 gm/cc will approximately give rise to gravity anomaly of :
    • A. 

      5 mgal

    • B. 

      15 mgal

    • C. 

      25 mgal

    • D. 

      50 mgal

  • 11. 
    Relationship of geometrical and gravitational flattening of Earth is given by :
    • A. 

      Gauss Theorem

    • B. 

      Green's Theorem

    • C. 

      Hayford's Theorem

    • D. 

      Clairaut's Theorem

  • 12. 
    The Bouguer anomaly over an isostatically compensated region is :
    • A. 

      Zero

    • B. 

      Positive

    • C. 

      Negative

    • D. 

      Same as isostatic anomaly

  • 13. 
    Magnetic equator coincides with the Geomagnetic equator.
    • A. 

      True

    • B. 

      False

  • 14. 
    SI unit of manetic induction is
    • A. 

      Tesla

    • B. 

      Gauss

    • C. 

      Oesterd

    • D. 

      None of above

  • 15. 
    The magnetic domains are due to :
    • A. 

      Covalent bonds

    • B. 

      Doping

    • C. 

      Hysteresis loss

    • D. 

      Spin excange interaction

  • 16. 
    Terrain correction is not generally applied to magnetic field data .
    • A. 

      True

    • B. 

      False

  • 17. 
    Curie point temperature for Haematite is :
    • A. 

      578 degree celsius

    • B. 

      670 degree celsius

    • C. 

      550 degree celsius

    • D. 

      None of these

  • 18. 
    Which of the following exhibits negative magnetic susceptibility ???
    • A. 

      Pyroxene

    • B. 

      Quartz

    • C. 

      Olivine

    • D. 

      Biotite

  • 19. 
    To derive magnetic field from gravity field , the poisson relation can be used only when the direction of magnetization is :
    • A. 

      Horizontal ( 0 degree)

    • B. 

      45 degree

    • C. 

      60 degree

    • D. 

      Vertical ( 90 degree)

  • 20. 
    Gravity measurement is made on a ship sailing at the speed of 6 knots in the direction N650E at 200N latitude. The Eotvos correction (in mGal) is :
    • A. 

      + 38.5

    • B. 

      + 24.5

    • C. 

      - 35.5

    • D. 

      -39.5

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