實驗目的：
研究光控原理。
實驗器材：
無弦琴。
實驗過程：
1、將電源插頭插入插座，打開電源開關。
2、手指并攏，擋住鍵盤上的小孔，注意聽。
3、實驗完畢，斷開220V電源開關并小心取下電源插頭。
探究問題：
1、手擋住了光線，為什么會聽到琴聲？
2、同樣做擋光的動作，為什么聽到的音調不同？
3、手擋光的位置不同，對實驗有怎樣的影響？
4、手擋光的時間長短不同，對實驗有怎樣的影響？
實驗結論與體會：
（以下由學生總結并交流，也可由教師引導得出。）
注意事項：
演奏簡單樂曲時，手在換位時應快速向后拉，手應距孔近些。
Musical instrument without the strings
Experimental purpose:
Researching the light controlling principle
Experimental equipment:
Musical instrument without the strings
Experimental process:
1.Connect the power supply, and turn on the switch.
2.Close the fingers to cover the eyelet in the fingerboard, and listen carefully.
3.Cut off the power supply and pull out the switch carefully.
Researching issues:
1.Why can we hear the sound with the hand shielding the light?
2.Why the sound is different again stopping the light?
3.What is the influence on the experiment at the different site of the hand stopping the light?
4.What is the influence on the experiment with the different time of stopping the light?
Experimental conclusions and the experience:
The followings can be concluded and discussed by the students, or guided to get by the teachers
Caution:
When play the simple music, the hand should quickly pull backward when changing the place, and the hand should be near the eyelet.
