题干

已知一台直流电动机两端的电压为6V,通过电动机的电流为2A,线圈的电阻为0.5欧,则在1min内电动机消耗的电能及产生的热量分别为(  )

A:720J  120J

B:720J  720J

C:720J  600J

D:600J   120J

上一题 下一题 0.0难度 选择题 更新时间:2019-11-22 04:01:23

答案(点此获取答案解析)

A

同类题2

阅读下面的文言文,回答文后各题。
                                                                                                  桃花源记 

                                                                                                     陶渊明
        晋太元中,武陵人捕鱼为业,缘溪行,忘路之远近。忽逢桃花林,夹岸数百步,中无杂树,芳草鲜美,落英缤纷,渔人甚异之。复前行,欲穷其林。
        林尽水源,便得一山,山有小口,仿佛若有光,便舍船从口入。初极狭,才通人,复行数十步,豁然开朗。土地平旷,屋舍俨然,有良田美池桑竹之属。阡陌交通,鸡犬相闻。其中往来种作,男女衣着,悉如外人。黄发垂髫,并怡然自乐。
        见渔人,乃大惊,问所从来。具答之。便要还家,设酒杀鸡作食。村中闻有此人,咸来问讯。自云先世避秦时乱,率妻子邑人来此绝境,不复出焉,遂与外人间隔。问今是何世,乃不知有汉,无论魏晋。此人一一为具言所闻,皆叹惋。余人各复延至其家,皆出酒食。停数日,辞去。此中人语云:“不足为外人道也。”
         既出,得其船,便扶向路,处处志之。及郡下,诣太守,说如此。太守即遣人随其往,寻向所志,遂迷,不复得路。
         南阳刘子骥,高尚士也,闻之,欣然规往。未果。寻病终。后遂无问津者。

同类题3

阅读理解

    I still remember my first day at school in London and I was half-excited and half-frightened. On my way to school I wondered what sort of questions the other boys would ask me and practiced all the answers: “I am nine years old. I was born here but I haven't lived here since I was two. I was living in Farley. It's about thirty miles away. I came back to London two months ago.” I also wondered if it was the custom for boys to fight strangers like me, but I was tall for my age. I hoped they would decide not to risk it.

    No one took any notice of me before school. I stood in the center of the playground, expecting someone to say “hello”, but no one spoke to me. When a teacher called my name and told me where my classroom was, one or two boys looked at me but that was all.

    My teacher was called Mr. Jones. There were 42 boys in the class, so I didn't stand out there, either, until the first lesson of the afternoon. Mr. Jones was very fond of Charles Dickens and he had decided to read aloud to us from David Copperfield, but first he asked several boys if they knew Dickens' birthplace, but no one guessed right. A boy called Brian, the biggest in the class, said: “Timbuktu”, and Mr. Jones went red in the face. Then he asked me. I said: “Portsmouth”, and everyone stared at me because Mr. Jones said I was right. This didn't make me very popular, of course.

    “He thinks he's clever,” I heard Brian say.

    After that, we went out to the playground to play football. I was in Brian's team, and he obviously had Dickens in mind because he told me to go in goal. No one ever wanted to be the goalkeeper.

    “He's big enough and useless enough.” Brian said when someone asked him why he had chosen me.

    I suppose Mr. Jones, who served as the judge, remembered Dickens, too, because when the game was nearly over, Brian pushed one of the players on the other team, and he gave them a penalty (惩罚). As the boy kicked the ball to my right, I threw myself down instinctively (本能地) and saved it. All my team crowded round me. My bare knees were injured and bleeding. Brian took out a handkerchief and offered it to me.

    “Do you want to join my gang (帮派)?” he said. At the end of the day, I was no longer a stranger.