What is the self-inductance of a coil in which an induced emf of 2V is set up when the current changes at the rate of 4 As-1 ?
Correct answer: B. 0.5H
- A. 0.5 mH
- B. 0.5H
- C. 2.0H
- D. 8.0H
Explanation
The self-induced emf satisfies ε = L(di/dt), so L = ε/(di/dt) = 2 V/(4 A s^-1) = 0.5 V s A^-1 = 0.5 H. The unit henry is equivalent to volt-second per ampere. Students may choose c by dividing the rate of current change by the emf instead of rearranging the formula.
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About Faraday's Law
Faraday's law states that an induced electromotive force equals the rate of change of magnetic flux linkage through a circuit. Questions cover changing field, area, angle or motion, the negative sign associated with Lenz's law, and the distinction between induced emf and the current that may flow in a closed circuit.
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