Which of the following is a characteristic of a profilometer?

A profilometer is an instrument specifically designed to measure the surface profile of a material. The process involves using a stylus that physically contacts the surface being analyzed. As the stylus moves across the surface, it traces the contours and variations, providing a detailed record of the surface topography. This method allows for precise measurements of roughness and other surface characteristics, which are critical for quality control in manufacturing and engineering processes.

The other choices do not align with the primary function of a profilometer. Measuring electrical resistance pertains to electrical testing instruments, weighing parts relates to scales or balance equipment, and analyzing chemical composition falls under the domain of spectrometers or chemical analysis tools. Thus, the unique operation of a profilometer using a stylus is what distinguishes it and defines its primary purpose in assessing surface profiles.