题干

有一个额定电压为2.8V,功率约为0.8W的小灯泡,现要用伏安法描绘这个灯泡的如图1I﹣U图线,有下列器材供选用:

A.电压表(0~3V,内阻6kΩ)

B.电压表(0~15V,内阻30kΩ)

C.电流表(0~3A,内阻0.1Ω)

D.电流表(0~0.6A,内阻0.5Ω)

E.滑动变阻器(10Ω,2A)

F.滑动变阻器(200Ω,0.5A)

G.蓄电池(电动势6V,内阻不计)

①用如图2所示的电路进行测量,电流表应选用____.滑动变阻器应选用____.(用序号字母表示)

②通过实验测得此灯泡的伏安特性曲线如图1所示.由图线可求得此灯泡在正常工作时的电流为____ A.

③若将此灯泡与电动势6V、内阻不计的电源相连,要使灯泡正常发光,需串联一个阻值为____Ω的电阻.

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D,E,0.28,11.4

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    IPhone owners are vainer(虚荣)and spend more on clothes and grooming(仪容)than those who have BlackBerrys and Android phones, new research claims.BlackBerry owners earn the most and are more likely to have long-term relationships, while people with Android handsets are most creative and the best cooks.

    The study, carried out by TalkTalk Mobile, surveyed 2,000 owners of the three major smartphone brands to determine whether the choice of handset was an extension(延伸) of their personality. The study rated users in various walks of life using a point scoring system including personalities, daily habits and the type of industries they work in.

    Other results from the study found that people with an iPhone are more image conscious and generally consider themselves more attractive than those with other handsets. They are most likely to describe themselves as adventurous, bright and are most likely to work in media, publishing and education. They also believe their boss rates them highly. Apple owners also tend to have done more travelling and are the most active on social media sites.

    BlackBerry owners were found to be the least punctual(准时的), but despite putting in the least hours at work they are the most active phone user—sending more texts and making more calls in the average day than any other phone user. They are more social and have more friends overall. They also earn nearly two and a half thousand pounds a year more than other smartphone owners, with an average salary of $27,406. BlackBerry users classed themselves so loud and mainly work in the health, finance or property sectors. They were also found to drink more tea and coffee each day than any other phone user.

    Android owners were found to watch more TV than others and drink the most alcohol—consuming more in an average week than iPhone and BlackBerry drinkers. They have the most jobs in engineering, the government and public services and environmental services. They have the best manners and are more shy and relaxed than their counterparts.

    Dan Meader, Director of Mobile at TalkTalk, said,“Many of us have our mobile phones on us almost constantly so they do become an extension of us in many ways. It's interesting to see then how the choice in handset may reflect different aspects of personality and the results do show some unusual difference