问题 填空题

如如图所示,是小明同学在网上查阅的一幅某种型号的家用白炽灯泡电流与电压关系的图象.通过分析图象可知:灯泡的电阻随着电压的升高而______;这只灯泡在220V电压下工作时,消耗的电功率是______W;这只灯泡两端电压是110V时,灯丝电阻是______Ω.(计算结果保留一位小数)

答案

(1)由 R=

U
I
,通过图象可以直接看出,电阻是并非定值,电压不同电阻也不同,电压升高,电阻增大,是由于受到了温度的影响;

(2)通过图象得出,220V电压对应的电流是0.18A,则消耗的电功率P=UI=220V×0.18A=39.6W;

(3)通过图象得出,110V电压对应的电流是0.15A,则此时灯泡的电阻R=

U
I
=
110V
0.15A
≈733.3Ω.

故答案为:增大、39.6、733.3Ω.

阅读理解

Adventure in Africa

by Connie Lee Berry

Ages 7-9  85 pages  Kid's Fun Press  December 2007

Adventure in Africa is written for children aged between 7 and 9 and may just be my favorite book in the Incredible Journey Series. In this book the two main characters Max and Sam are taken to an African Safari camp. Even with all the care taken by the staff to ensure the safety and comfort of the camp, things do go wrong and the two brothers find themselves rescuing an elephant and their tour guide, while braving the native wildlife and habitat of Africa.

Adventure in Africa is one of four books in this series of fluent readers’ paperback travel adventure books by Connie Lee Berry. The font(字体) is quite large and there are roughly a dozen maps, images and pictures in the book, which will attract younger readers. As an extra attraction, the back cover of the book lists some activities for children to do.

The animal photos were exciting, especially when the boys were able to ride an elephant! The pictures on the cover look like regular photos of family vacations. A large, interactive (互动的) companion website (www.ijbooks.com) allows readers to join in activities, contests and a club.

The price of the book is only $3.95 (US) now,$1 lower than before, and Adventure in Africa is a bargain. Hurry up to order one.

60. The book Adventure in Africa is written for _________.

A. all the readers  B. young parents   C. young kids  D. high school students

61. From the first paragraph we get to know _________ of the book.

A. the general idea B. the design      C. the author          D. the price

62. The last word in the passage ‘bargain’ probably means ‘something _________.

A. cheap            B. expensive       C. useful           D. priceless

63. The purpose of the writer is _________.

A. to tell readers something about Africa       B. to ask readers to join in contests

C. to introduce the book                       D. to attract young readers to buy it  

问答题