A2L Item 238

• Description: Identify the situations having an induced Emf.
• Goal: Reason with Faraday's law
• Source: 283-720 Faraday's Law
• Keywords: Electromagnetism, Voltage

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The question for students:

For which of the following is there an induced emf?

1. A conducting rod is pulled on conducting rails that are placed in a uniform magnetic field directed into the page.
2. A conducting loop moves through a uniform magnetic field directed into the page.
3. A conducting loop rotates in a uniform magnetic field directed into the page.
4. A conducting loop moves in a magnetic field produced by an infinite current-carrying wire.

1. A only
2. A and B only
3. A and C only
4. A and D only
5. B and C only
6. A, B, and C
7. A, C, and D
8. All of them
9. None of the above

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Commentary for teachers:

Answer

(3) Viewing the various cases using the Lorentz force law helps students understand why current flows in those loops experiencing a change of magnetic flux.

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