Fields D.4 Electromagnetic Induction (id: 09a0dcb0b)

本题目来源于试卷: Fields D.4 Electromagnetic Induction，类别为 IB物理学

[单选题]
The current $I$ in the conductor wire $X$ is decreasing which induces currents both in loops $Y$ and $Z$. The conductor wire and the loops lie in the same plane.


What is the direction of the induced currents in loop $Y$ and loop $Z$?

A. Loop Y is clockwise ; Loop Z is clockwise
B. Loop Y is anti-clockwise ; Loop Z is clockwise
C. Loop Y is clockwise ; Loop Z is anti-clockwise
D. Loop Y is horizontal ; Loop Z is anti-clockwise


参考答案:  B


本题详细解析:
Explanation:

Using the right-hand rule, one can determine the direction of magnetic fields on loops Y and Z due to the current in the wire.

The magnetic field on loop Y is in the direction out of the page, and the magnetic field on loop Z is in the direction into the page. Both decrease as the current in the wire decreases, so magnetic flux decreases for both loops Y and Z.

According to Lenz' law, a current is induced on the loop Y in an anti-clockwise direction, so it opposes the change in the flux. Likewise, according to Lenz' law, a current is induced on the loop Z in a clockwise direction, so it opposes the change in the flux.

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