A Flat Rectangular Loop of Wire Is Placed Between the Poles

question 23

Multiple Choice

A flat rectangular loop of wire is placed between the poles of a magnet, as shown in the figure. It has dimensions $w = 0.60 \mathrm {~m}$ and $L = 1.0 \mathrm {~m}$ , and carries a current $I = 2.0 \mathrm {~A}$ in the direction shown. The magnetic field due to the magnet is uniform and of magnitude $0.80 \mathrm {~T}$ . The loop rotates in the magnetic field and at one point the plane of the loop makes a $30 ^ { \circ }$ angle with the field. At that instant, what is the magnitude of the torque acting on the wire due to the magnetic field?

• A) \(0.83 \mathrm {~N} \cdot \mathrm { m }\)
• B) \(0.30 \mathrm {~N} \cdot \mathrm { m }\)
• C) \(0.40 \mathrm {~N} \cdot \mathrm { m }\)
• D) \(0.96 \mathrm {~N} \cdot \mathrm { m }\)
• E) \(0.48 \mathrm {~N} \cdot \mathrm { m }\)

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