A straight conductor of length 0.5 m moves at 4 m per second perpendicular to a field of 0.2 T. The emf induced across its ends is
Correct answer: A. 0.4 V
- A. 0.4 V
- B. 0.1 V
- C. 4 V
- D. 2.5 V
Explanation
The motional emf is BvL, that is 0.2 multiplied by 4 multiplied by 0.5, giving 0.4 V. The formula assumes the conductor, the field and the motion are mutually perpendicular; otherwise only the perpendicular components count. This is the elementary form of Faraday's law, since the conductor sweeps out area at a rate vL.
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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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