Which test measures the hardness of a material?

The Rockwell test is specifically designed to measure the hardness of materials. This test operates by pressing a hard, pointed indenter into the material's surface under a specified load and then measuring the depth of the indentation made by the indenter. The depth of this indentation correlates directly to the hardness of the material, allowing for a straightforward quantification of its resistance to deformation.

The method is particularly popular due to its efficiency, ease of use, and ability to provide immediate readings, making it suitable for a wide range of materials. Rockwell hardness tests can be performed on metals, plastics, and several other materials using different scales (like A, B, C, etc.) that denote various load levels and indenters used in the process.

Other tests mentioned in the options serve different purposes. The Braille test is not relevant to material hardness assessment; it is more about tactile reading for visually impaired individuals. The tensile test evaluates a material's strength by measuring how much it can be stretched before failing, while the impact test assesses a material's toughness by determining how much energy it can absorb before fracturing. Each of these tests provides valuable insights into material properties, but none specifically measures hardness like the Rockwell test does.