QGD-400氣動定值器QGD-300.J-FG3實驗器

 J-FG₃立式金屬線脹系數(shù)實驗器

  儀器利用彈性梁的彎曲，測定金屬材料的楊氏模量。儀器由在基座上相對移動的兩個平行刀口及擱在上面的彈性鋼梁組成，鋼梁中段套著具有刀口向下的矩形杠，它的下端，可懸掛砝碼，當懸重P作用于鋼梁而使梁彎曲時，其弛重量可通過上面安排的砝碼顯示表準確讀取。從而計算出鋼梁材料的楊氏模量

配合光杠可精確測量微小的位變，如長度、厚度及角度的變化等。                         

  QGD-400氣動定值器QGD-300.J-FG3實驗器技術參數(shù)：                                           （1）放大倍率：30^x                          

（2）物鏡孔徑：42mm                      

（3）視距乘常數(shù)：100                   

（4）視力場角：1°26’                   

（5）視距：1000mm    （6）調焦方式：內調焦

Structure and basic properties:

       QGD-400氣動定值器QGD-300.J-FG3實驗器本儀器為一大型音叉，由整塊的鋼材切削而成。在兩叉枝的頂端，裝置記錄筆尖一對，以供記錄波紋之用。叉柄固著于木質底板上的Ω型底坐上，在兩叉枝間距叉頂約三分之一處，裝置一電磁鐵，在左側叉枝的外側配備斷續(xù)接觸器，接通電流后，配合音叉的振動，形成勵磁線圈斷續(xù)通電，致使電磁鐵產生間斷吸力，驅使音叉作長期的振動。本音叉頻率約為100周/秒，每具音叉的實際頻率數(shù)均用硬印標出。標出的頻率數(shù)據(jù)就是是音叉頂部裝有一對記錄筆尖的頻率，如將此等附件連同螺絲全部卸去，則頻率約增加4分之3周。由于音叉叉枝質量較大，故在實驗中如弦振動駐波試驗等，負荷稍有變動時，對頻率的影響不大。

This instrument is a large tuning fork made from the cutting of one-piece steel material. A pair of recording pen-points is mounted at the top of two branches for the purpose of recording ripples. Fork handle is fixed on the Ω type seat of wooden bottom plate, one electromagnet is arranged between two fork branches and about one third away from the fork top, and an intermittent contactor is mounted at the outside of left-side fork branch. After the power supply is switched on, it is possible to form excitation coil, provide intermittent electricity, cause the electromagnet to produce intermittent suction, and drive the tuning form to produce long-term vibration. The frequency of tuning fork is 100 cycle per second, and the actual frequency number of each of tuning fork is marked with embossing seal. The marked frequency data equals to the frequency of a pair of recording pen points mounted at the top of tuning fork, and the frequency may increase 3/4 cycle, provided that these accessories and other screws are completely dismantled. Due to the larger mass of tuning form branch, slight changes in load may not have significant impact on frequency in such experiment as string vibration standing wave test.

QGD-400氣動定值器QGD-300.J-FG3實驗器使用方法：