问题 问答题

已知某玩具电动机的线圈电阻为1.5Ω,若将线圈直接接到电压为3V的电路中(不让线圈转动),通过线圈的电流是多少?当电动机正常工作时,你认为通过线圈的电流是比这个电流值大还是小?请设计一个实验来验证,写出你所用的器材,并简述你的方法.

答案

由欧姆定律I=

U
R
可得:

I=

3V
1.5Ω
=2A,即通过线圈的电流是2A;

我认为:电动机正常工作时,通过线圈的电流比这个2A电流值小.

实验器材:电源、开关、导线、电动机、电流表;

实验方法:将这些器材连成一个串联电路,先用电流表测出电动机线圈不转时的电流,再用电流表测出电动机正常工作时的电流,比较两次电流的大小即可.

阅读理解

Elaine Yu Yee-nee, 15, Creative Secondary School

Lockers are designed in a way to hide their contents for a reason. Otherwise, they’d have open fronts like cupboards. Searching students’ lockers would be total invasion(侵犯) of privacy. Having a locker is more than having a place to store your stuff. A locker also gives you the freedom to keep certain things hidden. These can include harmless personal items like diaries, letters and photos. Searching lockers could discomfit students and others might make fun of them.

Yes, lockers are school property(财产). But that doesn’t give schools the right to inspect lockers as they please. While students are using lockers, they have the right to keep their contents private. Teachers could ask for permission to take a look inside a student’s locker and if the student is OK with that, then it would be fine. Searching students’ lockers without their permission would result in the loss of trust.

I doubt that students who have something dangerous to hide, such as weapons or drugs, would put them in their lockers. They would not want to risk being caught so easily.

Giving schools the right to search lockers would not help catch those who commit crimes. But it would certainly create an environment in which students would be embarrassed to have their belongings shown in public for no good reason.

Ronald Ling Pak-ki, 20, University of Hong Kong

Many students see their lockers as personal property. They would never agree that schools should have the right to inspect their lockers. But I think schools have an absolute right to do so.

It is the schools that actually own the lockers. Students just use them to store some of their things safely and conveniently. There are clear rules on what items students can and cannot keep in their lockers. Schools have both the duty and the right to check if students are following the rules.

I don’t think school authorities would decide to search a student’s locker unless they felt the need to do so. They might, for instance, suspect students of hiding drugs. To make sure that the process remains open and fair, only authorized teachers should have the right to search lockers. The search should be carried out in such a way as not to embarrass students in front of others.

小题1:What are .the two students talking about?

A.How to make sure schools are safe.

B.Whether there are crimes in schools.

C.Whether schools can search students’ lockers.

D.How to establish trust between teachers and students.小题2:The underlined word could be replaced by ___.

A.embarrass

B.frighten

C.worry

D.challenge小题3:According to Elaine, school lockers ____.

A.are students’ personal property

B.should be changed into cupboards

C.are likely to hold some dangerous things

D.can be searched with students’ permission小题4:Which of the following would Ronald agree with?

A.Students won’t hide drugs in lockers.

B.Students use lockers but don’t own them.

C.Students should not put personal things in lockers.

D.Students may forbid teachers to inspect their lockers.

阅读理解与欣赏