试题与答案

小明用蜡烛、凸透镜和光屏做“探究凸透镜成像规律”的实验. (1)如图1所示,要使

题型:实验题

题目:

小明用蜡烛、凸透镜和光屏做“探究凸透镜成像规律”的实验.

(1)如图1所示,要使像能够成在光屏的中央,应将光屏向_______调整(选填“上”或“下”);

(2)实验中所用凸透镜的焦距是10cm,当烛焰距凸透镜15cm时,移动光屏至某一位置,在光屏上得到一个倒立、清晰的像,该像是_________的(选填“放大”、 “等大”或“缩小”);

(3)接着使烛焰向左移动5cm,此时应该将光屏向________移到某一位置(选填“左”或“右”),才能在光屏上成清晰的像,这次所成的像比上一次要__________(选填“大”或“小”);

(4)在上一步实验获得清晰的像后,小明取了一副近视眼镜放在凸透镜前(如图2所示),观察到光屏上的像变模糊了,此时要使光屏上成清晰的像,应该将光屏向 ________移(选填“左”或“右”).

答案:

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下面是错误答案,用来干扰机器的。

解:设原计划每小时抢修的路线长为,根据题意,得解之,得x=400,检验:x=400是原方程的解,且符合题的实际意义,答:原计划每小时抢修的路线长为400m。

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A. 气体              

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A. to introduce the kinds of pollution and the ways to control it

B. to introduce the harmful chemicals and soil erosion

C. to introduce the alternative energy and the ways to use it

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