问题 选择题

一定值电阻,通过2C的电荷量时,消耗的电能是8J,若在相同时间内通过4C的电荷量,那么电阻两端的电压和消耗的电能分别为(       )

A.4V,16J

B.8V,16J

C.4V,32J

D.8V,32J

答案

答案:D

分析:(1)已知电阻丝在通过2C的电量时,消耗的电能是8J,根据W=UQ变形可求出电压;当在相同的时间内通过电阻丝的电量是4C时,根据I=可知,当时间相同,由电荷时的关系可知电流关系,因为电阻不变,根据U=IR,由电流关系可知电压关系,即可求出电阻丝两端所加电压U;

(2)已知通过电阻丝的电量是4C,电阻丝两端所加电压U已求出,根据W=UQ可求出电阻丝在这段时间内消耗的电能W.

解答:解:因为电阻丝在通过2C的电量时,消耗的电能是8J,所以此时电压为:

U′===4V,

当在相同的时间内通过电阻丝的电量是4C时,根据I=可知,I=2I′,

根据U=IR可知,电阻不变,此时电阻丝两端电压:U=2U′=8V,

电阻丝在这段时间内消耗的电能:

W=UQ=8V×4C=32J.

故选D.

阅读理解

Around the World in Eighty Days is a classic Adventure novel by Jules Verne. The story starts in London in 1872. One day in the Reform Club, Phileas Fogg, a wealthy gentleman, accepts a wager(赌注) for £20,000, which he will receive if he travels around the world in 80 days.

Phileas Fogg sets off immediately, with his servant Passepartout. They reach Suez(苏伊士) quickly. While landing in Egypt, he is watched by a British detective named Fix, who is in search of a bank robber. Because Fix mistakes Fogg for the criminal, he follows secretly, as they are getting on a ship to Bombay.

After more than 20-days of travelling, they arrive in San Francisco, and then get on the train to New York. During that trip, the train is attacked by Indians, who take Passepartout away. With some soldiers’ help, Fogg succeeds in freeing his companion. To make up for the lost time, Fogg and his companion hasten on to New York, and catch the steamer for the crossing of the Atlantics. They arrive in Ireland in time to reach London before the deadline. However, once on British soil again, Fix arrests Fogg. Although the misunderstanding is quickly cleared up—the actual bank robber had been caught several days earlier. Fogg has missed the train and returns to London five minutes late, sure that he has lost the wager.

However, the next day Fogg learns from the priest that he is mistaken in the date, which he thinks Sunday but which actually is Saturday, due to the fact that they gained a full day on their journey around the globe, by crossing the International Date Line. Fogg immediately sets off for the Reform Club, where he arrives just in time to win the wager.

小题1:The reason that Fix wants to arrest Phileas Fogg is that                  .

A.Phileas Fogg is the bank robber whom Fix is trying to catch

B.Phileas Fogg doesn’t have a passport for his travels

C.Fix mistakenly takes Phileas Fogg for the bank robber

D.Fix intends to prevent Fogg from winning the wager小题2:During his time in America, Phileas Fogg spends a lot of “unexpected” time             .

A.travelling across the continent of America

B.rescuing his companion from the Indians

C.waiting for the ship back to London

D.getting rid of the pursuing of Fix小题3:Does Phileas Fogg win the wager at last? Why?

A.No. Because he doesn’t get to the Reform Club before the deadline.

B.Yes. Because he is not the bank robber; it’s a misunderstanding.

C.No. Because he wastes too much time during his trip.

D.Yes. Because he arrives at the Reform Club before the deadline.

计算题