Question

"Whenever magnetic flux linked with a closed coil changes, an induced emf is setup in the coil and lasts as long as the change in magnetic flux continues." This is:

• A. Lenz’s Law
• B. Faraday’s first law of electromagnetic induction
• C. Faraday’s second law of electromagnetic induction
• D. Biot-Savart law

Hint:

Faraday’s First Law = Emf is induced when magnetic flux changes. Second Law gives the magnitude: \( \text{emf} = -\dfrac{d\Phi}{dt} \).

Answer 1

The Correct Option is B

The question refers to a fundamental principle in electromagnetism, specifically related to the behavior of magnetic fields and electric circuits. Let us analyze the options provided:

• Lenz’s Law: This law states that the direction of induced current in a closed loop will be such that it opposes the change in magnetic flux that produced it. While related, it does not primarily describe the situation.
• Faraday’s first law of electromagnetic induction: Faraday's first law states that whenever the magnetic flux linked with a closed circuit changes, an electromotive force (emf) is induced in the circuit. This mirrors the situation described and is indeed the correct identification.
• Faraday’s second law of electromagnetic induction: This law quantifies the induced emf, stating it is proportional to the rate of change of the magnetic flux linkage. It is a quantitative expression, not qualitative as described.
• Biot-Savart law: This law describes the magnetic field generated by an electric current in a nearby space, and is not related to the problem context.

Hence, the statement given corresponds to Faraday’s first law of electromagnetic induction, which describes the induction of emf due to change in magnetic flux linkage.