问题 问答题

某同学用如图所示的电路,研究通过导体的电流与导体两端的电压、导体电阻间的关系.若保持电源电压的大小和电阻箱R1的阻值不变,移动滑动变阻器R2的金属滑片 P,可测得不同的电流、电压值,如表1所示.然后,他又改变电阻箱R1的阻值,测得相应的电流值,如表2所示.

(1)分析表1中的数据可知:______.此时电阻箱接入电路的电阻为______Ω.

(2)分析表2中的数据可知:电流与电阻不成反比,其原因是______,正确的操作方法是:改变电阻箱R1的阻值后,______.

(3)在实验操作过程中,某同学发现,闭合开关后电压表的示数接近电源电压,电流表的示数为零,则电路的故障可能是______.

表1                             

实验序号 U1/V  I/A
10.2
1.50.3
20.4
表2

实验序号  R1  I/A
30.5
60.33
90.25

答案

(1)由表1数据可以看出,导体中的电流随电压的增大而增大,并且成倍数的增大,得出结论:在电阻一定时电流与电压成正比;

根据R=

U
I
可知,三组数据对应的电阻都为5Ω,即此时电阻箱接入电路的电阻为5Ω.

(2)他在改变电阻箱R1的阻值时,R1两端的电压也随之变化,此时电压和电阻都变化,测得的电流值的变化就说不清是哪个因素的变化引起的,没有用控制变量法,所以得出的结论是不准确的;正确的操作方法是:改变电阻箱R1的阻值后,移动滑片直到电压表示数不变(依然为1.5V)读出电流表示数.

(3)电压表的示数接近电源电压说明与电压表两接线柱串联的电路是通路,电流表的示数为零说明电路,故电路故障为与电压表并联的电阻箱断路(接触不良).

故答案为:(1)当电阻相同时,通过导体的电流与导体两端的电压成正比;5;

(2)没有控制电阻箱(R1)两端的电压相等;移动滑片直到电压表示数不变(依然为1.5V)读出电流表示数;

(3)电阻箱断路(接触不良).

阅读理解

Our spiritual intelligence quotient (精神智商),or SQ, helps us understand ourselves, and live fuller, happier lives.

Though we're all born with SQ, most of us don’t even realize that we have it. Fortunately, you don't have to sign up for classes to learn how to improve your SQ. Here are some simple steps that can lead you to this new level of understanding.

Sit Quietly. The process of developing spiritual intelligence begins with solitude (独处) and silence. To tune in to your spirit, you have to turn down the volume (强度) in your busy, noisy, complicated life and force yourself to do nothing at all. Start small by creating islands for silence in your day. In the car, instead of listening to the music, use the time to think. At work, shut the door to your office between meetings, take a few breaths and let them out very, very slowly. Enjoy the stillness in your home after the kids are finally in bed.

Step Outside.  For many people, nature sets their spirit free. Go outside to watch a beautiful sunset. If you are walking with the dog, take the time to admire flower in bloom; follow the light of a bird and watch clouds float overhead.

Ask Questions of Yourself. Ask open-ended questions, such as "What am I feeling? What are my choices? Where am I heading?"

But don't expect an answer to arrive through some supernatural form of e-mail. "Rarely do I get an immediate answer to my question," says Reverend Joan Carter, a Presbyterian minister in Sausalito, California. “But later that day I suddenly find myself thinking about a problem in a perspective(角度) I never considered before.”

Trust Your Spirit. While most of us rely on gut(本能的) feeling to realize danger, spiritual intelligence pushes us, not away from, but towards some action that will lead to a greater good.

68. The passage is mainly about           .

A. what your SQ is and in what way it can benefit our life

B. what your SQ is and in what way it can be improved

C. the relationship between your SQ and your life

D. advantages and disadvantages of SQ

69. The underlined phrase "tune in to your spirit" in the third paragraph probably means to _____.

A. get your spirit relaxed                   B. keep up your spirit

C. keep seated quietly                      D. change your spirit

70. The author mentions the example of Reverend Joan Carter to show that            .

A. there are no immediate answers to your questions

B. e-mails can't keep working out a problem

C. the more questions you ask, the better answers you'll get      

D. changing your way of thinking might help you solve a problem

71. From the passage, we can know that the most important thing to improve your SQ is      .

A. a peaceful mind    B. deep thought   C. spare time and hobbies   D. good spirits

名词解释