The diagram shows in cross-section a circular loop of wire which rotates at a steady rate about a diameter 0 w…

Question

The diagram shows in cross-section a circular loop of wire which rotates at a steady rate about a diameter 0 which is perpendicular to a uniform B field. The maximum induced emf occurs when the point X on the loop passes:
(A) a
(B) b
(C) c
(D) d

Accepted Answer

正確答案為 C。 感應電動勢最大的時刻，是磁通量為零、變化率最大的時候：X 轉到 c 時，線圈平面與 B 平行（Φ = 0），X 的速度方向與 B 垂直，切割磁力線最快。 (A) X 在 a 時線圈平面（圖中直立）與水平磁場垂直，磁通量最大但變化率為 0，感應電動勢為 0；此時 X 的速度與 B 平行，不切割磁力線。容易誤以為「磁通量最大 → 電動勢最大」。 (B) b 介於 a 與 c 之間，速度與 B 夾斜角，電動勢不是最大值。

The diagram shows in cross-section a circular loop of wire which rotates at a steady rate about a diameter 0 which is perpendicular to a uniform B field. The maximum induced emf occurs when the point X on the loop passes:

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The diagram shows in cross-section a circular loop of wire which rotates at a steady rate about a diameter 0 which is perpendicular to a uniform B field. The maximum induced emf occurs when the point X on the loop passes:

逐選項解析

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理化 相關題目

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理化相關題目