A decrease in conductivity of a material indicates what change in resistivity?

When the conductivity of a material decreases, it implies that the material is becoming less effective at allowing electric current to flow through it. Conductivity (σ) and resistivity (ρ) are inversely related, with conductivity being the reciprocal of resistivity. This relationship can be expressed mathematically by the formula σ = 1/ρ.

Therefore, if conductivity decreases, resistivity must increase to maintain the inverse relationship. Thus, a decrease in conductivity directly results in an increase in resistivity. This is why the answer indicating an increase in resistivity is the correct interpretation of the given scenario.

Understanding this relationship between conductivity and resistivity is crucial in Eddy Current Testing as it plays an essential role in determining the characteristics of the material being tested and how it will respond to induced eddy currents.