问题 选择题

矩形线框在匀强磁场内匀速转动过程中,线框输出的交流电压随时间变化的图像如图所示,下列说法中正确的是(    )

A.2s末线框平面垂直于磁场,通过线框的磁通量最大

B.1s末线框平面垂直于磁场,通过线框的磁通量变化最快

C.此交变电流方向在1min内改变30次

D.将此交变电流接一标有:“36V,40W”的白炽灯时,此灯能正常发光

答案

ACD

2s末电动势为零,此时线框平面垂直于磁场,通过线框的磁通量最大,A正确;1s末感应电动势最大,引时线框平面平行于磁场方向,通过线框的磁通量变化最快,B错误;周期为4s,一周内电流方向改变两次,则1min内改变30次,C正确;交流电的最大值为V,有效值为36V,D正确。

选择题
阅读理解

     The results of LIT CRIT magazine's poll (民意测验) to find the greatest American authors of all time. Top five most popular biographical details.

     ① Mark Twain

     1835 — 1910

     The Adventures of Huckleberry Finn

     A boy travels down the Mississippi with a runaway slave.

     Real name: Samuel Clements. He was a printer and a river-boat pilot before moving to San Francisco to work as a reporter. He traveled widely, and the expectations of his world tour are recorded in The Innocents Abroad.

     ② Herman

     Melville1809 —1891

     Moby DickStory Of a sea captain fascinated with finding a famous white whale.

     After working as a teacher and a farmhand, in1839 he went to sea and joined the U. S. Navy. His books reflect his life at sea and his thoughts on faith and God. During his life, he was more famous in Great Britain than in the U. S.

     ③ Ernest Hemingway

     1899 — 1961

     For Whom the Bell Tolls

     Based on the writer's experiences as a reporter in the Spanish Civil War.

     Best known for his novels, but it was his short stories that first attracted attention. He wrote about

hard men (bullfighters, boxers, hard-drinkers) and showed how courage and honesty are often lost in a

modern society without hope and faith.

     ④ F. Scott Fitzgerald

     1896 —1940

     Tender is the Night

     Moving stories of a psychiatrist (精神病医师) and his wife that reflects the writer's own marriage to

Zelda.

     The author of The Great Gatsby wrote his first story for a school paper at the age of 13. He travelled

widely and made vacations on the French Riviera. His problems with alcohol and depression are

described in The Crack-up.

1. What is the name of the author who once worked on a farm?

A. Mark Twain                    

B. Herman Melville

C. F. Scott Fitzgerald            

D. Ernest Hemingway

2. What is the title of the book about an author's experiences in Spain?

A. Moby Dick.                    

B. The Adventures of Huckleberry Finn

C. For Whom the Bell Tolls.          

D. Tender is the Night.

3. What is the most popular book by the writer of The Innocents Abroad?

A. The Adventures of Huckleberry Finn.

B. Tender is the Night

C. Moby Dick.

D. For Whom the Bell Tolls.

4. Which writer wrote his first story for a school paper?

A. Edgar Allen Poe                

B. Herman Melville

C. Ernest Hemingway              

D.F. Scott Fitzgerald