Resistivity measurement is a technique used to determine how strongly a material opposes the flow of electric current. This property, known as resistivity, is crucial in various fields, including electronics, geology, and materials science. By applying a known voltage across a sample and measuring the resulting current, the resistivity can be calculated using Ohm's law. Different methods exist for measuring resistivity, such as the four-point probe technique and van der Pauw method. These methods help ensure accurate results by minimizing the effects of contact resistance. Understanding resistivity is essential for selecting materials for electrical applications and assessing soil properties in geotechnical engineering.