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A conducting wire frame lies in a magnetic field pointing into the page, and the field strength is increasing at a constant rate. Determine the directions of the induced currents in the two arms AB and CD.
- B to A and D to C
- A to B and C to D
- A to B and D to C
- B to A and C to D
Correct answer: B to A and D to C
Solution
The into-page flux is increasing, so by Lenz's law the induced current opposes it by creating flux out of the page, i.e. it circulates anticlockwise. Following an anticlockwise sense around the frame gives current from B to A in one arm and from D to C in the other.
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