Abstract:

A Young’s modulus experimental instrument is designed based on the principles of light interference and single-slit diffraction. According to the change rule of fringes of light interference and diffraction, the tiny length change of metal wire under tension can be measured, and then the high precision measurement of Young’s modulus of metal wire is realized. To satisfy the experimental conditions for interference of light, a pneumatic tension adjusting device is designed to replace weights, in which the shaking problem of the instrument is solved and the stepless adjustment of tension change and the reading of tension directly from the electronic scale are realized. The instrument also make a simple traditional mechanical experiment change into a comprehensive experiment combining mechanics and optics for measuring Young’s modulus, which enriches the experimental content, broadens the students’ vision, and improves their comprehensive ability to analyze and solve problems.

Key words: Young’s modulus, minor length change, pneumatic tension adjustment, interference of light, single-slit diffraction