(6分)閱讀下面短文

會發(fā)光的電磁翹翹板

小明制作了如圖1 6(a)所示的電磁翹翹板參加學校的科技節(jié)活動.該電磁翹翹板是在兩端封閉的透明塑料管中放有一塊磁性很強的磁鐵,塑料管外繞有金屬絲作為線圈,在線圈兩端并聯(lián)兩只發(fā)光二極管(符號),其電路如圖l 6(b)所示.二極管具有單向?qū)щ娦,電流只能從二極管的正極流入,負極流出.演示時,將塑料管上下翹動,磁鐵便在線圈中左右移動,相當于線圈導體在磁場中做切割磁感線運動,這時會看見兩只發(fā)光二極管輪流發(fā)光.

  請回答下列問題:

(1)電磁翹翹板中發(fā)光二極管輪流發(fā)光是根據(jù)    原理工作的,    也是根據(jù)這一原理工作的(填“電動機”或“發(fā)電機").

 (2)電磁翹翹板上下翹動時,為什么發(fā)光二極管會輪流發(fā)光?

(1)電磁感應;發(fā)電機。

 (2)因為當磁鐵向低處滑動時,磁鐵串過閉合線圈,線圈相對在做切割磁感線運動,產(chǎn)生感應電流,此時,電流通過兩個二極管中的一個,故該二極管發(fā)亮;當另一端低時,磁鐵又向相反方向串過線圈,產(chǎn)生相反方向的電流,故另一個二極管也會發(fā)亮。所以,二極管會輪流發(fā)光。

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科目:初中物理 來源: 題型:058

(6分)閱讀下面短文

會發(fā)光的電磁翹翹板

小明制作了如圖1 6(a)所示的電磁翹翹板參加學校的科技節(jié)活動.該電磁翹翹板是在兩端封閉的透明塑料管中放有一塊磁性很強的磁鐵,塑料管外繞有金屬絲作為線圈,在線圈兩端并聯(lián)兩只發(fā)光二極管(符號),其電路如圖l 6(b)所示.二極管具有單向?qū)щ娦,電流只能從二極管的正極流入,負極流出.演示時,將塑料管上下翹動,磁鐵便在線圈中左右移動,相當于線圈導體在磁場中做切割磁感線運動,這時會看見兩只發(fā)光二極管輪流發(fā)光.

請回答下列問題:

(1)電磁翹翹板中發(fā)光二極管輪流發(fā)光是根據(jù)    原理工作的,    也是根據(jù)這一原理工作的(填“電動機”或“發(fā)電機").

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(6分)閱讀下面短文

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