31. What is the main limitation of Ground Penetrating Radar (GPR)? A. Poor resolution B. Not effective in dry sand C. High cost D. Ineffective in conductive soils Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D Solution: GPR struggles in highly conductive soils like clays due to rapid signal attenuation.It performs best in dry, sandy, or resistive environments.
32. In which method are current electrodes used to introduce electric current into the ground? A. Magnetic B. Seismic C. Electrical resistivity D. Gravity Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Electrical resistivity methods inject current into the ground through electrodes to measure the potential difference and infer subsurface resistivity.
33. What does a low resistivity value usually indicate? A. Dry sand B. Granite C. Clay or saturated soil D. Igneous rock Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Clay and saturated soils conduct electricity well, thus showing low resistivity.High resistivity is typical of dry, dense rocks.
34. Which method can detect voids or sinkholes beneath roads? A. Gravity survey B. Magnetic survey C. Seismic reflection D. Resistivity imaging Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D Solution: Resistivity imaging can detect anomalies caused by voids, cavities, or sinkholes as these areas contrast with surrounding material in resistivity.
35. Which parameter is derived from magnetic surveys? A. Water content B. Porosity C. Magnetic intensity D. Seismic velocity Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Magnetic intensity reflects the total field strength and is used to detect magnetic anomalies due to ferromagnetic materials underground.
36. What is the primary use of gravity methods in engineering geology? A. Mineral detection B. Moisture content mapping C. Detection of subsurface density variations D. Determining groundwater pH Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Gravity methods detect changes in subsurface density which helps locate voids, faults, and rock interfaces.
37. What kind of waves are Rayleigh waves? A. Surface seismic waves B. Electromagnetic waves C. Radio waves D. Gravity waves Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A Solution: Rayleigh waves are a type of surface seismic wave that travel along Earth's surface and are useful in shallow geophysical surveys.
38. Which geophysical method is most suitable for detecting metallic ore bodies? A. Seismic refraction B. Resistivity C. Magnetic survey D. GPR Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Magnetic surveys are highly effective in detecting metallic ores with magnetic properties like magnetite or pyrrhotite.
39. Which configuration provides higher resolution in shallow resistivity surveys? A. Dipole-dipole B. Schlumberger C. Wenner D. Gradient array Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A Solution: The dipole-dipole array offers excellent resolution for mapping shallow lateral variations in subsurface resistivity.
40. In seismic methods, which factor influences wave velocity the most? A. Temperature B. Pore water color C. Density and elastic properties D. Sunlight Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Seismic wave velocity depends primarily on the density and elastic modulus of the material through which the wave travels.
