关键词: 扭转力矩, 简谐振动, 光杠杆, 地磁场, 图像分析技术

Abstract: When a coil hanging under the copper wire，due to the torque of the copper wire for harmonic vibration，simple harmonic vibration cycle can be calculated for the shear modulus of copper wire. After the coil is energized，it is affected by the geomagnetic moment in the earth s magnetic field. By using the optical lever amplification principle，the shear modulus of the copper wire can be calculated by measuring the small deflection angle before and after the coil is energized. In order to reduce the measurement time，the coil can be measured in a very short time by measuring the harmonic vibration image before and after the captured coil is energized，so as to measure the shear modulus of the copper wire. The method of kinematics，mechanics，optics，electromagnetism principle and image analysis technique is used to measure the shear modulus of the material，which improves the measurement accuracy，reduces the measurement cost and is easy to operate. It is very suitable for popularization in university physics teaching.

Key words: Torsional moment, simple harmonic vibration, optical lever, geomagnetic field, image analysis technique