Inductive proximity sensors detect ferrous targets at greater distances than nonferrous targets such as aluminum.

• A. Copper
• B. Aluminum
• C. Gold
• D. Wood

Answer: (B)

Inductive proximity sensors detect metal by needing to disturb a magnetic field created around a coil. How far they can sense depends on how the target interacts with that field. Ferrous materials, like iron or steel, have high magnetic permeability, so they channel the field and cause a stronger disturbance, allowing detection from a greater distance. Nonferrous metals, such as aluminum, have much lower permeability, so the field disturbance is weaker and the detectable distance is shorter. In this context, aluminum serves as a clear nonferrous example, showing the contrast to ferrous targets. Wood isn’t metal and isn’t detectable by inductive sensors, while copper and gold are also nonferrous but aren’t the specific example highlighted here.