问题
填空题
小彩灯上标有“36V 36W”，将它接在实际电压为40V的电源上使用，应当串联一个阻值为______Ω的电阻才能正常发光．
答案
（1）小彩灯正常发光时的电流I=
=PL UL
=1A；36W 36V
（2）串联电阻两端电压UR=U-UL=40V-36V=4V，
串联电阻阻值R=
=UR I
=4Ω；4V 1A
故答案为：4．
搜题请搜索小程序“爱下问搜题”
小彩灯上标有“36V 36W”，将它接在实际电压为40V的电源上使用，应当串联一个阻值为______Ω的电阻才能正常发光．
（1）小彩灯正常发光时的电流I=
=PL UL
=1A；36W 36V
（2）串联电阻两端电压UR=U-UL=40V-36V=4V，
串联电阻阻值R=
=UR I
=4Ω；4V 1A
故答案为：4．
| 任务型阅读。 阅读下列材料，从所给的五个句子中，选出正确的句子填空，把所选句子抄写在原文当中， 使短文通顺，完整。 | |
| A rich American went into a shop in London. He wanted to buy a nice watch. 1._____ But the shop owner asked 500 dollars for it. Just then a young man came in, took the watch out of the owner's hand and run out with it. 2._____ . When the owner ran out into the street, the young man was already gone. The American went on. At the next corner, 3._____ "Do you want to buy a fine watch,sir?" he said in a low voice," It's made in Germany. It's only 100 dollars. "4._____ ", he thought. The American paid at once and went back to his room with the watch. 5._____ . His friend took a look at his watch and started to laugh. He said, you are a fool. This watch isn't worth even 10 dollars. | |
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