如图所示的装置探究“导体产生的热量与电阻大小的关系”。两瓶煤油中都浸泡着一段金属

题型:探究题

问题:

如图所示的装置探究“导体产生的热量与电阻大小的关系”。两瓶煤油中都浸泡着一段金属丝,烧瓶A中的金属丝是铜丝,电阻比较小,烧瓶B中的金属丝是镍铬合金丝,电阻比较大。

(1)这两个烧瓶中所盛煤油的质量应该_________________;

(2)实验中不用水而用煤油的原因是:_________________;

(3)电路采用这种连接方式的目的是: ________________;

(4)合上开关后,经过一段时间,两电阻丝产生热量的多少是通过_______ 反映出来的;

(5)实验中,发现B烧瓶中温度计的示数升高的快。这表明:在电流和通电时间相同的情况下,导体的电阻越_______ ,产生的热量越多。

考点:焦耳定律的变形公式的应用比热容的概念
题型:探究题

Car accidents happen everywhere every day and are the main cause of injury in the United States. In order to control the increasing(增长) accidents, many states have passed tough laws. Also, car manufacturers(制造商) have been trying to make safer cars to save lives.

However, as there are more and more cars and drivers on the road, these safety measure (安全措施)are not enough to stop the increasing car accidents. The National Highway Traffic Safety Administration (管理部门)reports that a car accident happens every 10 seconds in the United States.

Car accidents may be caused by different reasons. Some accidents are caused by driver’s tiredness and illness or drunk driving. Some may be caused by speeding or running a red light. When this happens, by the time the driver realizes what has happened, it is usually too late. As for ages, young drivers usually have enough experience while elderly drivers of react slowly. Mechanical defects (机械毛病)such as a broken brake(刹车) are another cause of car accidents. Poor road and weather conditions can also be a cause.

Talking about different causes of car accidents can help us know what precautions(预防措施) to take beforehand. We should tell our friends or family members not to drive in poor health or after drinking wine. We should tell teenager drivers to be careful with road and weather conditions and let elderly friends understand their driving limitation(局限性)。Besides, we should have our car checked regularly(规律地). The most important thing for us to remember, however, is that we should always follow the traffic rules.

小题1:What has the government done to try to control the increasing car accidents?

A.They try to make safer cars.

B.They try to build more roads.

C.They have passed tough traffic laws.

D.They make drivers have their car examined every month.小题2:What does the underlined word” elderly” possibly mean?

A.Middle-aged

B.Young

C.Rather old

D.Teenage小题3:Which of the following causes is different from the other three?

A.Tiredness

B.Illness

C.Drinking

D.a broken brake小题4:Which has nothing to do with a driver’s age?

A.Teenager drivers.

B.Not knowing the traffic rules

C.Reacting slowly

D.Driving slowly.小题5:In order to avoid accidents caused by mechanical defects, we should ___________.

A.not run a red light.

B.drive the car when we are in good health

C.not drive when we are too old.

D.have our cars examined regularly.

题型:探究题

碘剂既可用以治疗甲亢,又可引起甲亢。

题型:探究题

道岔标记含钢轨编号、轨距、支距、钢轨伤损等标记。

题型:探究题

(1)有以下四种物质①22g二氧化碳;②8g氢气;③1.204×1024个氮气分子;④4℃时18g水;它们所含分子数最多的是______,所含原子数最多的是______,质量最大的是______,常温时体积最大的是______(填序号).

(2)等质量的二氧化硫和三氧化硫,它们的物质的量之比为______,所含的硫原子数之比为______,所含的氧原子数之比为______.

(3)147gH2SO4的物质的量是______;0.5molH2SO4的质量是______g,其中含有______molH,含有______molO;2molH2SO4中含有H2SO4分子数为______个,含氢原子数为______个.

题型:探究题

生后24小时排绿色胎便,3-4天排空,逐渐过渡到稀黄的糊状便。如果排便延迟或不排便并呕吐、腹胀应及时找医生诊治。

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