问题 填空题

有一只电压表,量程已知,内阻为RV,另有一个电池(电动势未知,但不超过电压表的量程,内阻可忽略),请用这只电压表和电池,再用一个开关和连接用的导线,设计出测量某一高值电阻的实验方法,(已知RX的值和RV相差不大).

(1)画出电路图(在方框内)

(2)简要地写出测量步骤______

(3)由测量得到的数据导出电阻RX的计算式为______.

答案

(1)电路图如图

(1)测量步骤:①连接如图所示电路;②闭合开关,读出此时电压表示数E为电源电动势;③断开开关,读出此时电压表示数U.

(3)根据闭合电路欧姆定律,闭合开关时应有电压表示数为E,断开开关,应有E=U+

U
R V
R,解得R=
(E-U
)R V
U

故答案为:(1)如图

         (2)①连接如图所示电路;②闭合开关,读出此时电压表示数E为电源电动势;③断开开关,读出此时电压表示数U.

         (3)

(E-U
)R V
U

综合题
写作题

阅读下面的短文, 然后按照要求写一篇150词左右的英语短文。

Getting up early has been regarded as a good habit since ancient times. Many years ago, people thought that if we went to bed early and got up early, we would be energetic the whole day. So, getting up early is of great importance to us all.

In fact, morning is the best time of a day. In the morning, the air is the freshest and people are usually in the best conditions.

Many of us may have the experiences that we memorize some things more quickly and accurately in the morning than at any other time of the day. If we do some morning exercise or only take a short walk in the morning, we can build our bodies and become much healthier.

Also we will have enough time to make a plan and get ready for our work or study of the day if we get up early. However, if we get up late, we’ll probably have to do everything in a great hurry.

Let us remember getting up early is a good habit and try our best to keep it. If we stick to getting up early every day, we will certainly benefit a lot from it.

[写作内容]

1. 以约30个词概括短文的主要内容;

2. 然后以约120个词就“早起还是晚起好”的主题发表看法, 内容包括:

(1) 你赞成早起还是晚起及理由;

(2) 你的父母或教师有何看法;

(3) 你如何看待他们的看法。

写作要求]

1. 可以使用实例或其它论述方法支持你的论点, 也可以参照阅读材料的内容, 但不得直接引用原文中的句子;

2. 标题自定。

[评分标准]

概括准确, 语言规范, 内容合适, 篇章连贯。