关键词: 单摆法, 电磁感应, 重力加速度, 周期

Abstract: In this paper, single pendulum method is combined with electromagnetic induction principle in the experiments. A permanent magnetic sphere as the pendulum ball is used and a multiturn coil is placed directly under it. When the pendulum ball moves in simple harmonic motion, magnetic flux in the coil is disturbed and thereby a periodic induced electromotive force is generated. A filter module was used to suppress the noise and the electromotive force signal was collected by an oscilloscope. As a result, the pendulum period could be determined accurately by collecting electromotive force signal. Furthermore, the distance between the coil and pendulum ball was changed in order to evaluate the effect of electromagnetic damping. The measurement was repeated at different distance and the measured period data was found to be independent on the distance configurations. It indicated that electromagnetic damping could be ignored which was in agreement with our semiquantitative analysis. The local gravitational acceleration measured in this paper was good consistent with the reference value.

Key words: pendulum method, electromagnetic induction, gravitational acceleration, period