问题 填空题

10秒内通过某导体横截面的电荷量为6库,电流做功功率为1.8瓦,则通过该导体的电流为   安,该导体两端的电压为     伏。当它连接在电压为4.5伏的电源两端,该导体的电阻为     欧。

答案

0.6、3、5

题目分析::(1)通过该导体的电流

(2)导体两端的电压

(3)导体电阻

由于导体的材料、长度、横截面积不变,当导体两端电压是4.5V时,导体电阻是20Ω.

点评:本题考查了求电流、电压、电阻等问题,是一道基础题,熟练掌握基础知识,把题中所给数据代入公式解题即可.

判断题
阅读理解

阅读理解。

     Every year thousands of people get hurt or die when they are crossing the road. Most of these people are

old people and children. Old people often get hurt or die because they can't see or hear very well. Children

usually meet with accidents because of their carelessness. They forget to look and listen before they cross the

road.

     How can we lessen (减少) traffic accidents? All of us must obey the traffic rules. For the drivers, they

shouldn't drive too fast. If they drive too fast, it will be very difficult to stop the cars in a very short time. For

the pedestrians (行人), it's very important to be careful when they are walking on the road. Therefore, when

we walk across the road, we must try to walk along the pavements. We must stop and look both ways before

crossing the road. Look left first, next look right, and then look left again. Only when we are sure that the road

is clear can we cross it. The right way to cross the road is to walk quickly. It's not safe to run. If people run

across the road, they may fall down. Teens should try to help children, old people or blind people to cross the

road, and never play in the street.

1. Which of the following is NOT the right way to cross the road?

A. Stop and look both ways.

B. Run quickly.

C. Make sure that the road is clear.

D. Walk quickly.

2. Why do most old people often get hurt or die when they are crossing the road?

A. Because they are not careful.

B. Because they forget to look and listen.

C. Because they can't see or hear very well.

D. Because they often run across the road.

3. As a student, you can _____ to try to lessen traffic accidents.

A. help children to cross the road

B. play in the street carefully

C. run across the road quickly

D. let drivers drive slowly