热点试题

[ 考点 ] 九年级物理考点:电路图及元件符号

  • 电路图:
    用规定的符号表示电路连接情况的图叫做电路图;

    几种常见的元件符号如下:


  • 常见元器件作用:
    元件 作用 常见器件
    电源 提供电能的装置,将其他形式的能量转化为电能 干电池、蓄电池和发电机等
    用电器 用电来工作的设备,将电能转化为其他形式的能 电灯、电炉、电视机、电铃、电冰箱等
    开关 用来接通或断开电路,起控制电路的作用 拉线开关、拨动开关、闸刀开关等
    导线 将电源、用电器、开关连接起来,形成电流的通路 金属导线

  •  

  • 2016-05-16 | 0

    [ 数学 ] 售货员阿姨粗心地把4.50元 的钢笔标成了0.45元,钢笔卖出后,会造成什么后果?

    售货员阿姨粗心地把4.50元 的钢笔标成了0.45元,钢笔卖出后,会造成什么后果?

    2016-05-21 | 0

    [ 数学 ] 下列叙述正确的是( )A.互质的两个数没有公因数B.两个分数大小相等,分数单位也一定相等C

    下列叙述正确的是(  )
    A.互质的两个数没有公因数
    B.两个分数大小相等,分数单位也一定相等
    C.小兰完成的作业量一定,她已完成的作业和未完成的作业量成反比例
    D.两个面积相等的三角形,不一定能拼成一个平行四边形

    2016-05-21 | 0

    [ 数学 ] 已知数列{an}满足a1=a(a>2),an+1=2+an,n∈N*.(1)求证:an+1

    已知数列{an}满足a1=a(a>2),an+1=
    2+an
    ,n∈N*
    (1)求证:an+1<an
    (2)若a=
    3
    2
    2
    ,且数列{bn}满足an=bn+
    1
    bn
    ,bn>1,求证:数列{lgbn}是等比数列,并求数列{an}的通项式;
    (3)若a=2011,求证:当n≥12时,2<an<2+
    1
    2011
    恒成立.(参考数据210=1024)

    2016-05-24 | 0

    [ 数学 ] (本题满分16分)如图,在六面体中,,,.求证:(1);(2).

    (本题满分16分)如图,在六面体中,.

    求证:(1);(2).

    2016-05-24 | 0

    [ 语文 ] 将下列句中画线部分的内容换成一个恰当的成语写下来。     1.可是更多的时候,身无分文的

    将下列句中画线部分的内容换成一个恰当的成语写下来。     
    1.可是更多的时候,身无分文的我只能装作选书的样子,偷看几则小故事,然后悄悄跑掉了事。 (    )    
    2.西双版纳曾经有过威严的气势使人敬畏的象兵。    (    )     
    3.世界各地的观光者接连不断地到来,在这从天而降的巨大水帘面前,置身于细细的水雾之中,感受这不受外界影响的美好境地的清新空气。    (    )(    )     
    4.我痛哭了几天,心事沉重,吃不下饭心事重重,睡不好觉。(    )(    )

    2016-05-26 | 0

    [ 语文 ] 下列各句中没有语病的一项是 [     ] A、 截至27日,利比亚反对派已经控制的黎波里

    下列各句中没有语病的一项是[    ]
    A、 截至27日,利比亚反对派已经控制的黎波里绝大部分区域,但双方的战斗仍在南部市郊持续胶着。虽然 “全国过渡委员会”25日宣布已完全接管的黎波里市的治理,但实际上首都仍处于无政府状态。
    B、美国联邦储备委员会开动“印钞机”,客观上造成美元贬值,推进以美元计价的国际农产品价格飙升。
    C、昌九城际铁路开通后,昌九两地居民上午11时前交寄的中国邮政文件类快递件,搭乘昌九城际列车,当天下午6时前就能送到收件人手上。
    D、长宁区新华街道老年公寓已正式投入使用,此举将标志着长宁区“为老惠民行动”拉开帷幕。

    2016-05-27 | 0

    [ 英语 ] 听句子,从A、B、C三个选项中选择与你所听到的内容相同或相近的选项。 (     )1. 

    听句子,从A、B、C三个选项中选择与你所听到的内容相同或相近的选项。
    (     )1.  A. parent   
    (     )2.  A. 83662817 
    (     )3.  A. thought   
    (     )4.  A. Anyway,  I'll tell
                   you the secret.
    (    )5.  A. John doesn't like football. 
    B. present 
    B. 83662617
    B. caught  
    B. If you don't tell the secret
        to others, I'll tell you.
    B. John prefers volleyball to football.
    C. pleasant   
    C. 83262817                               
    C. bought  
    C. If you tell the secret to others,
        I'll tell you. 
    C. John prefers football to volleyball.
            

    2016-05-28 | 0

    [ 英语 ] 阅读理解。      Miss Evans taught physics in a Lon

    阅读理解。
         Miss Evans taught physics in a London school. Last month she was explaining to her class about
    sound, and she decided to test them to see how successful she had been in her work. She said to them,
    Now, I have a sister in Washington. If I was calling her on the telephone, and at the same time you were
    20 meters away and listened to me from the other side of the street, who could hear what I said earlier,
    my sister or you? And why?
        The cleverest boy at once answered, "Your sister, Miss Evans, because electricity (电) travels faster
    than sound waves(波)." That's very good, Miss Evans answered, but then one of the girls put up her hand, and Miss Evans said, Yes, Betty?
         "I don't think so. Betty said, Your sister would hear you earlier because when it's eleven o'clock here,
    it's only six o'clock in Washington."
    1. Miss Evans was teaching her class ______.     
    A. about sound                      
    B. to hear some strange sound
    C. about electricity                    
    D. how to say time
    2. She wanted to make her students know______.      
    A. whether she could hear her sister in Washington
    B. whether her students could hear her from 20 meters away
    C. which was faster, London or Washington
    D. electricity travels faster than sound waves
    3. The cleverest boy thought that______.
    A. sound waves travel faster than electricity
    B. they would hear her sister in Washington first
    C. Miss Evans's question wasn't right
    D. Miss Evans's sister would hear her earlier
    4. Miss Evans______.       
    A. thought Betty's answer was much better
    B. thought the cleverest boy's answer wasn't so good
    C. was satisfied with what the girl had said
    D. was satisfied with(对...感到满意) what the cleverest boy had said
    5. Betty thought the cleverest boy was wrong, because______.
    A. clocks in Washington showed a different time from those in London
    B. electricity was slower than sound waves
    C. they were only 20 meters away from the telephone
    D. electricity travels as fast as sound waves

    2016-05-28 | 0

    [ 英语 ] 听录音,请你在对应图片下标出序号。             (     )       (

    听录音,请你在对应图片下标出序号。
               
    (     )       (     )        (     )         (     )         (     )           (     )         (     )

    2016-05-28 | 0