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A rigid wire consists of a semicircular portion of radius R and two straight sections. The wire is partially immerged in a perpendicular magnetic field B = B 0 k ˆ as shown in figure. The magnetic force on the wire if it has a current i is: y z x

1. 2iBR j ˆ
2. – 2iBR j ˆ
3. iBR j ˆ
4. – iBR j ˆ

Correct answer: – 2iBR j ˆ

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