问题 实验题

在“探究导体的电阻跟哪些因素有关”的实验中。

(1)小明的猜想是:①电阻可能与导体的材料有关;

小亮的猜想是:②电阻可能与导体的温度有关;

小敏的猜想是:③电阻可能与导体的长度有关;

根据你掌握的电学知识,你认为:

④电阻还与                有关。

(2)右图是三位同学为上述探究活动准备的实验器材,他们已经完成了部分实物的连接。若电阻受温度的影响可以忽略,要探究猜想①,应该控制____________和____________不变;要探究猜想③,应该选用导线________和导线________(填导线的代号字母)进行实验。

答案

(1)横截面积   (2)长度、横截面积    a 、c

考点:

专题:探究型实验综合题.

分析:(1)影响电阻大小的因素有:导体的材料、长度、温度和横截面积.

(2)在探究实验时要通过控制变量法去判断,探究导体的电阻与导体的材料是否有关,应控制其长度和横截面积不变;同理要想探究导体的电阻与导体的长度是否有关,应控制导体的材料和横截面积不同.

解答:解:(1)影响电阻大小的因素有:导体的材料、长度、温度和横截面积.

(2)探究电阻与材料的关系时,要选取的电阻丝必须长度、横截面积、温度相同,材料不同.探究电阻与长度的关系时,要选用材料和横截面积都相同、长度不同的a、c两电阻丝;

故答案为:(1)导体的横截面积;(2)导体的长度和横截面积;a;c.

点评:物理学中对于多因素的问题,常常采用控制因素的办法,把多因素的问题变成多个单因素的问题,分别加以研究.

阅读理解

Ifhas anyone noticed how, with the passage of time, one’s relationship with one’s grown-up daughters and sons becomes changed? I’ve been aware of this for some time but I’m not quite sure how to deal with it.

Take the kitchen sink for example.

Following a family get-together at my place, I walked into the kitchen to find Kate, my daughter, carefully cleaning the sink.

“Don’t do that; what are you doing that for?” I said, unhappy about the hidden criticism.

“Mum,” she said, “you really ought to put your glasses on when you clean the sink. Behind the tap here was black!”

But it’s not just things like kitchen sinks. Another time Kate arrived to pick me up to lunch. She looked at me and then asked, “Mum, why do you use brown eyebrow pencil when your hair is grey?”

A sudden memory of her, aged 14, going to her first mixed party flooded back. She had come in to say goodbye. For a moment I thought she’d been an accident. Both eyes were black. I remember suggesting that perhaps a little less eye make-up might be more effective.

Now I told her, “My hair used to be brown.”

“It looks absurd.(荒唐)”

“Mrs. Menzies had dark eyebrows with grey hair.”

“Yes, but you’re not Mrs. Menzies, are you?” she said triumphantly, as if that proved her point.

But a recent event made me realize that something really must be done.

She had returned home for a few weeks before getting married. One evening I went out on a dinner date. By the time my companion left me at the front door, it was about 2am. As I stepped in, an angry figure in a white nightgown(睡衣)stopped me.

“Well, what time of night is this to be coming home?” she shouted. “Where have you been? I’ve been worried sick!”

Shades of the past come back to disturb me. But what should I do about all this? Nothing, probably. Maybe, after all, it’s only a stage young people are going through.

小题1:The daughter thought her mother didn’t clean the kitchen sink well because of her       .

A.laziness

B.carelessness

C.unhappiness

D.poor-quality glasses小题2:From the passage we know the daughter        .

A.didn’t want to help with the sink

B.didn’t like brown eyebrow pencils

C.had an accident when she went to her first party

D.shouted at her mum because she came home late小题3:How does the mother feel after all these have happened?

A.Shocked.

B.Proud.

C.Envious.(嫉妒)

D.Confused.小题4:The author writes the stories to prove that ________.

A.their relationship became stronger

B.their roles changed as time passed

C.her daughter very much cared about her

D.her daughter got upset as she grew up

单项选择题