电Electricity （五年级 科学）

第七课：电 Electricity

• 电从哪里来？
• 认识完整电路。
• 什么是串联和并联电路（What's series and parallel circuits?)。
• 如何安全使用电器？

     diànyuán  gandiànchí     fādiànjī  xiǎoxíngfādiànjī  xùdiànchí    shuǐlìfādiànzhàn  tàiyángdiànchí
[1] 电 源(sources of electricity)：干电 池(battery)。发电 机(electrical generator)。小  型 发电  机。蓄电池(lead-acid battery)。水  力发电站(hydro-power)。太阳  电 池(solar power)。
    diànlù  tú
[2]电 路图(electrical circuits)。
                 diànlù  yuánjiànde fú  hào   dēngpào     gandiànchí     kāiguān  diànxiàn
[A]电路元件 的符号 (symbols in an electrical circuit)。灯泡(bulb)。 干电池(battery)。开 关(switch)。电 线(wire)。

    diànlù  zhonglèi              chuànliándiànlù               bìngliándiànlù
[3]电 路种类 (Types of electrical circuits)。（A）串联电 路(series circuit)。 （B）并联 电 路(parallel circuit)

串联电路(series circuit)：灯泡相继地连接，电流只有一条通路。如果一个灯泡坏了，电流不能流通，所以令一个灯泡也不会亮起来！



并联电路（parallel circuit)：灯泡并列地连接起来，形成两个分支电路。如果其中一个灯泡坏了，另一个灯泡还会继续发亮。


    ān quánshǐyòngdiànqì               bùgòngyòngchāzuò              zǐ xì  yuèdú ānquánshǐyòng shǒucè               bǎsǔnhuài
[4]安全  使用  电 器 (use electricity safely)。（A）不共 用  插 座。 （B）仔细阅 读安全 使用  手  册。 （C）把损 坏
dediànqì  sòngdàowéixiūzhōngxīn  xiāncā ganshǒucáijiē  chùchāzuò
的电 器送  到 维修中   心。（D）先  擦干手  才接触 插 座。

    yòngdiànbùdāngdehòuguǒ             chùdiàn            huǒhuàn
[5]用  电 不当 的后果(Danger of electricity)。 （A）触 电(electrical shock)。（B）火 患(fire)  

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Reference:
[.]

 Electricity:

We depend on electricity in our daily lives. Electricity has made our lives easier and more comfortable. There are many sources of electricity. Many appliances in our homes and schools use electricity. However. we must be very careful when using electrical appliances. Why?

Some electrical appliances use dry cells to make them work. Dry cells produce electricity. There are also other sources of electricity such as accumulator, dynamo and solar cell. They are examples of batteries.

Accumulators are used in vehicles such as motorcycles, cars and lorries. Dynamos generate electricity. They are used to light up the bulb of bicycle. Satellites get their electricity from solar cells. Solar cells transform light energy into electricity. We can also get electricity from hydroelectric power stations.

An electrical circuit is made up of a power source, wires and other components such as a bulb and a switch. The dry cell is a source of electrical energy for the circuit. A switch is used to break or complete a circuit. The wire allows electricity to flow through the circuit. The bulb lights up because electricity flows through it. 

Electricity is useful in our everyday life. Electrical appliances need proper handling because they can cause injury if they are not used properly. Mishandling of electrical appliances can cause. There are safety precautions that must be taken when using electrical appliances.

• Do not touch switches with wet hands.
• Do not connect too many electrical appliances to one power point.
• Do not repair electrical appliances by yourself.
• Do not use electrical appliances that are faulty.
   

[.] Electric circuits: