题干

如图所示,电路连接正确,通电后小磁针指向如图所示(涂黑端表示N极).请在图中标出螺线管的磁极、电源的“+”、“﹣”极,并画出螺线管的绕法(至少三圈).

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解:如图所示,小磁针的右端为N极,根据磁极间的相互作用规律可知通电螺线管靠近小磁针N极一端的S极,则通电螺线管的右端为N极.

再根据右手定则,伸出右手握住通电螺线管,使大拇指指示通电螺线管的N极(右端),则四指弯曲的方向为电流的方向.又电流从电源的正极流出经滑动变阻器、电流表流入螺线管,即电流由螺线管的右端流入,左端流出,故螺线管的绕法如图所示:

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    Watch a Funny Video

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    Take Walk Outside

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E. Keep Positive Relationships

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