The term resistivity refers to the electrical resistance of a material. Put simply this is the amount of resistance a material can put up against an electric current, most measurements are made with a resistance meter. A material that is regarded as being highly resistant impedes the flow of electron greatly; plastic and rubber are both examples of materials with high resistance. On the other hand a low resistant material will allow the flow of electrons freely; examples would be some metals and liquids such as water.



All materials have a specific resistance related to them, however a number of general rules mean that it is not always essential to utilise a resistivity meter. Metals and salt water are particularly conducive to allowing the free flowing of electrons; glass, plastic and rubber are the opposite. Due to the low resistance of metals, these are used for electrical wiring while wires are coated in plastic or rubber to avoid electric shocks and short circuits. In the electrical product industry the resistivity meter is used frequently to test the resistance of wires and electrical components.

Resistivity is not however the same as resistance; it is an equation that takes into account three separate factors. These three factors are resistance, area and length. The resistance is measured in Ohms and in most cases can be found using a table of resistance that contains information on a number of different materials. Area is the area of the wire or piece of material and shows how much space the electrons have to flow. Finally the length gives information on how far the electrons must travel. In terms of mathematics by multiplying the resistance and area and then dividing this number by the length will give the resistivity. Thankfully the resistivity meter does this without the need for a pen and paper.

It is not only the electrical manufacturing industry however that extensively measures resistivity. Surprisingly the mining industry also uses the meter regularly on rock formations. This is because rock formations that have large amounts of metal present in them will conduct the electricity. Hence by measuring resistivity, miners can find deposits more effectively. Subsequently the process of finding metals in the earth is made that less laborious and safer. The processes involve testing on the ground using handheld meter varieties as well a deep drilling that requires a far larger and more powerful resistivity meter.

The two methods of prospecting using electrical resistance are also subdivided into two categories, passive and active. Active prospecting is the process of adding a large electrical charge to the ground and then measuring the strength of the electrical field at a variety of points using electrodes. Passive is different in the way that it measures naturally occurring electrical fields as a result of chemical reactions taking place underground.

It is thanks to the resistivity meter that both of these techniques are deemed a valid way of prospecting for metal deposits in the ground. Apart from the mining industry this technology has helped in electrical manufacturing to build hardier, more effectively designed components and devices. Without the resistivity meter the mining process would be far more dangerous and difficult, and our electrical devices would not be as reliable. It may not be the most exciting of meters, but the impact it has had on a number of disparate industries should not be underestimated.