4. What did the explorers find?

A. The coastlines of South America and Africa could fit together.

B. The coastlines of North America and Africa could fit together.

C. The east coastlines of North America and the west coast of Europe could fit together.

D.The coastlines of North America and India could fit together.

(二)

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3. The last word of the third paragraph “tectonics” mean “________”.

A. study of construction

B. study of architecture

C. earth surface

D. structural geology

2. Which of the following is true according to the passage?

A. We didn’t see the Earth from far away until we saw the picture taken in the space.

B. Our ancient thought that the surface of the earth is still.

C. Alfred Wegener was not the first person to investigate the idea that the continents move.

D. The coastline of India and Africa fit together.

1. What does the writer mainly tell us in the passage?

A. The first breath-taking pictures of the Earth taken from space.

B. Human’s recognition of the earth’s surface.

C. The German scientist Alfred Wegener.

D. The early explorers’ discovery.

　　如图是一种建立在空间的太阳能电站向地球上固定区域供电的示意图。在太阳能收集板上铺设太阳能电池，通过光电转换把太阳能转换成电能，再经微波转换器将电流转换成微波，并通过天线将电能以微波的形式向地面发送。地面接收站通过天线把微波能还原成电能。

　　(1)如果太阳能电池的硅片能提供的电能为12kW/m²，巨大的太阳能收集板的总面积为5×10⁶m²，则太阳能电站的发电能力是多少kW？

　　(2)利用微波传输电能，实现了“无缆输电”。输电效率可达80%，若微波输电采用的频率是2450MHz。求微波的波长及地面接收站接收到的电能是多少kW？

　　解析：从题目和问题中可提取有用的信息并推导出公式，然后利用公式进行计算。

　　如图(甲)所示，光I从空气斜射如玻璃中，发生了折射现象，从图中可以看出折射角r小于入射角i。那么，一般情况下，i与r有什么定量关系呢？1621年，荷兰学者斯涅尔通过实验终于找到了i与r之间的规律，如图是光从空气进入玻璃中时，利用实验数据得到的sinr与sini的关系图象。

　　(1)在图(甲)中，画出光Ⅱ进入玻璃中传播的大致方向(如图)

　　(2)分析图象可得到的结论：　　　　　　　　　。

　　解析：从图中可以看出，横轴为sini，纵轴为sinr；通过图像可以看出二者成正比。

　　答案：(2)入射角的正弦和折射角的正弦成正比。

　　方法归纳：对于图像类题目，首先要看清图像的横轴和纵轴表示的是哪个物理量，然后再根据图像的形状来判断物理量之间的关系，从而确定问题的答案。

2．下表是某同学研究“电阻消耗的电功率与该电阻阻值之间的关系”时记录的实验数据，请你对表格中的数据进行分析，归纳出电功率与电阻的关系：_____________________。

　　解析：解答此题要找准表中各量的变化规律：电阻──逐渐变大，电压──不变，电流──逐渐变小，电功率──逐渐变小；且电功率和电阻成反比。

　　答案：在电压一定时，电阻消耗的电功率与该电阻阻值成反比。

　　方法归纳：认真分析表中各物理量的变化情况，特别是要找准变化量和不变量，并从中分析出各物理量之间的关系。

1．某实验小组在探究光的折射规律时，将光从空气分别射入水和玻璃，测得数据如下表：

空气中的入射角i	0°	30°	45°	60°
水中的折射角r	0°	22°	32°	40°
玻璃中的折射角	0°	17°	24°	30°

　　分析表格中的数据，你肯定能得出一些规律。请写出一条：_____________________。

　　解析：本题考查学生对数据的综合分析能力。解题时，可横向分析，也可纵向分析。

　　答案：(1)入射角为0°，折射角也为0°。(2)入射角增大，折射角也随着增大。(3)光从空气斜射入不同介质中的折射角不同。(4)光从空气斜射入其他介质时，折射角小于入射角。(5)光以相同入射角斜射入水和玻璃时，水中的折射角大于在玻璃中的折射角。

17．在中，，．

(Ⅰ)求的值；

(Ⅱ)设的面积，求的长． (Ⅰ)由，得，

由，得．

所以．

(Ⅱ)由得，

由(Ⅰ)知，

故，又，

故，．所以．