问题 选择题

小明将微风电风扇与小灯泡按如图所示的电路连接并进行实验,用手快速拨动风扇叶片,这时发现小灯泡发光,微风电风扇居然变成了“发电机”。关于该实验,下列说法正确的是(  )

A.小灯泡发光是把光能转化为电能

B.电风扇发电的原理是通电导线在磁场中受到力的作用

C.电风扇发电过程是把电能转化为机械能

D.电风扇发电的原理是电磁感应

答案

答案:D

电动机的原理是通电导体在磁场中受力,能量转化是电能转化为机械能;发电机的原理是电磁感应现象,能量转化是机械能转化为电能.

尽管电风扇里装的是电动机,但此题中是当作发电机用的,故说明的是磁场中运动的线圈可以产生电流,即电磁感应现象,其能量转化是机械能转化为电能.

阅读理解

阅读理解。

     We all know that money can't make us happy, but many times we act as if we'd be

happier with a bit more money. We are conditioned to want to be richer; we are trained

to want the latest style that television tells us; we want to earn more money because then

we'll have a good life.

     But none of that will make us happier. And the sad thing is that it can take us decades

of pursuing (追求) wealth and expensive things before we realize that. So what will bring

us happiness? Luckily, there are three things that don't cost anything. Here they are:

     Good relationships. We have a human need to be close with other human beings. Having

good, supportive friendships, a strong marriage or loving relationships with our family members

will make us much more likely to be happy. Therefore, take time, today, to stay with your

loved ones, to tell them what they mean to you, to listen to them, and to develop your r

elationships with them.

     Positive thinking. Optimism(乐观) is one of the best indicators of people who lead a

happy life. Happy people feel empowered, in control of their lives. So why not make

positive thinking a habit? In fact, this should be one of the first habits you develop.

     Flow. This is a popular concept on the Internet these days 一 the state we enter when

we are completely focused on the work or task. Having work and leisure(休闲)that gets

you in this state of flow will almost undoubtedly lead to happiness. People find the greatest

enjoyment not when they're passively mindless, but when they're absorbed in a mindful

challenge.

     If you are interested in some kind of work and keen on some kind of hobbies, it is not a

bad idea. Turn off the TV 一 this is the opposite of flow 一 and then go outside and do

something that truly makes you active.

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