问题 实验题

某物理“科技制作”小组装配一台小直流电动机,其额定电压5V,额定电流0.5A,线圈绕阻小于1。为了进一步研究其在一定电压范围内,输出功率与输入电压的关系,需要进一步做实验,请你帮助该小组完成该项工作。已知学校实验室提供的器材有:

直流电源E,电压6V,内阻不计;

小直流电动机M;

电压表V1,量程0~0.6V,内阻约3k

电压表V2,量程0~6V,内阻约15k

电流表A1,量程0~0.6A,内阻约1

电流表A2,量程0~3A,内阻约0.5

滑动变阻器R,0~10,2A;

电键S一只,导线若干。

(1)首先要比较精确测量电动机的线圈绕阻。根据合理的电路进行测量时,要控制电动机不转动,调节滑动变阻器,使电压表和电流表有合适的示数,电压表应该选        。若电压表的示数为0.1V,电流表的示数为0.2A,则内阻        ,这个结果比真实值偏         (选填“大”或“小”)。

(2)在图方框中画出研究电动机的输出功率与输入电压的关系的实验电路图。(标明所选器材的符号)

(3)当电压表的示数为4.5V时,电流表示数如图所示,此时电动机的输出功率是     W。

答案

①V1  0.5 小(3分) ②(4分)③1.72(4分)

(1)让滑动变阻器处于最大阻值处,电路中的电动机不转圈时最大电压为,所以选用V1  ,根据欧姆定律得电动机内阻为r=0.5,因为电流表测量的是电压表和电动机的总电流,所以电流测量值比真实值大,故测得的内阻偏小,

(2)采用分压法,电流表的外接法。

(3)根据1分度盘读法可得电流为0.40A,根据公式 .

单项选择题
阅读理解

A Nobel Prize is considered by most people one of the highest international honors a person can receive. As you know, the prizes were started by a Sweden called Sweden Alfred Nobel. Alfred Nobel was born in Stockholm, the capital of Sweden, and lived from 1833 to 1896.

Alfred Nobel was a chemist and inventor. He made two important inventions, so he became very rich. Although he was rich, Nobel was not a happy man. He never married or had children. Also, he was a sick man in large part of his life. Nobel died at the age of sixty-three. When he died, he left a fund of $9,000,000. The money was to be used in giving prizes to those who made outstanding achievement in physics, chemistry, medicine, literature, and the promotion(促进)of the world peace.

The first Nobel Prize were given on December 10th,1901, five years after Nobel’s death. Many famous people all over the world have been given Nobel Prizes for their achievements. Albert Einstein was one of them.

Each prize has three parts. The first part is a gold medal. Second, a winner of a Nobel Prize is given a diploma saying that he has been given the prize. The third part of the prize is a large amount of money---about $40,000.

Often a prize is given to just one person, but not always. Sometimes a prize is shared. It might be given to two or more people who have worked together. It is also sometimes true that a prize is not given at all if there is no outstanding achievement. In 1972, for example, not a Nobel Prize was given. It is the Nobel Foundation in Stockholm that decides whether to give the prize or not.

小题1:Most people think that Nobel Prize is ____ a person can receive.

A.the highest honor in the world

B.one of the highest international honors

C.a higher honor than others

D.as high as any other honor小题2:Alfred Nobel who started the Nobel Prize was _____.

A.a rich, happy and lucky man

B.a poor, unhappy and unlucky man

C.a poor, happy and lucky man

D.a rich unhappy and unlucky man小题3:A Nobel Prize is made up of ___.

A.a gold medal and a large amount of money

B.a gold medal and a diploma

C.a gold medal and a diploma and a large amount of money

D.a diploma and a large amount of money小题4:A Nobel Prize is given to ___ each year.

A.just one person

B.one person

C.not always one person

D.three persons小题5:When he died, Nobel left an amount of money ____.

A.to his wife and children

B.to the university he used to study in

C.to his parents and his studies

D.to be spent on setting five prizes