问题 选择题

理想变压器的原副线圈匝数之比为4:1,若在原线圈上加u=1410Sin100t(V)的交变电压,则在副线圈两端用理想交变电压表测得的电压是:

A.250V

B.352.5V

C.203.8V

D.327.5V

答案

答案:A

题目分析:原线圈两端的有效电压值为:,根据公式可得副线圈两端电压为,A正确

故选A,

点评:基础题,关键是会根据表达式求解有效值,然后根据公式求解

阅读理解

请阅读下面一篇文章,并按照要求匹配信息。注意:E=AB  F=AC  G=AD

On Monica & Hitesh’s wedding day, Monica’s mother gave her a newly opened bank saving passbook(银行存折) with $1000 deposit amount. Mother: “Monica, take this passbook.   1   When something happy and memorable happens in your new life, put some money in. Write down what it’s about next to the line. When you look back after years, you can know how much happiness you’ve had. ” 2   This was what they did after a certain time:

----- 7 Feb: $100, first birthday celebration for Hitesh after marriage

-----1 Mar: $300, salary raise for Monica

-----20 Mar: $200, vacation trip to Bali

----- 15 Apr: $2000, Monica got pregnant

-----1 Jun: $1000, Hitesh got promoted… and so on…

3   They didn’t talk much. They regretted that they had married the nastiest person in the world....

One day Monica talked to her Mother: “Mom, we can’t stand it anymore. We agree to divorce. I can’t imagine how I decided to marry this guy!!! ” Mother: “Sure, girl, that’s no big deal. Just do whatever you want if you really can’t stand it. But before that, do one thing first. Remember the saving passbook I gave you on your wedding day? Take out all money and spend it first.    4   

Monica thought it was true. So she went to the bank, waiting at the queue and planning to cancel the account. While she was waiting, she took a look at the passbook record. She looked, and looked, and looked.     5   Her eyes were then filled with tears. She left and went home, putting the passbook back to the safe.

A.However, after years, they started fighting and arguing for unimportant things.

B.Keep it as a record of your marriage life.

C.They had saved much money when they retired.

D.Then the memory of all the previous joy and happiness just came up her mind.E. Monica and her husband both thought it was a great idea.

F. Remember the saving passbook her mother gave her on the wedding day.

G. You shouldn’t keep any record of such a poor marriage.

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