Resistivity is termed as a measure of how strong a material opposes flow of electric current, magnetic rays, gamma rays or other ways that may be used. It is measured using a resistivity meter. When low, it means that the material has good conductance. Different land and water features are defined in terms of such measurements and quality to various forms of energy. Since the decade of 1930, different methods have been employed to take the measurements. The devices started as mechanical ones and have over time transformed into electrical devices due to technology improvements. The first ever device used in geophysical experiments was the Wenner array which had four probes arranged in a line. The probes were for voltage and current transmission and were placed at equal intervals. The device had its faults and was later improve to form the twin-probe array that is still in use today by archaeologists. The device had a disadvantage of conducting survey slowly and has since been improved to include many arrays. Geospatial engineers have also developed ones that do not require direct physical contact with the land being assessed. Another latest method in use by miners and engineers is audio frequency sensing through imaging. Electromagnetism has also been put to use for such purposes. They apply both magnetic and electric principles for taking the required details. Electric resistivity meter is by far the best equipment because it is accurate and can be used anywhere. The devices use the Doppler Effect to measure how long it takes to transmit through land and water and the results used to calculate the value for the soil or water. Some of the latest software developments include one that simulates different possible natural landscapes. The results gotten give an idea of how the topography might be and what challenges might be encountered. This way petroleum engineers get to discover oil and miners know where to find minerals.
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