A Flat Circular Wire Loop of Area $0.25 \mathrm {~m} ^ { 2 }$

Multiple Choice

A flat circular wire loop of area $0.25 \mathrm {~m} ^ { 2 }$ carries a current of $5.0 \mathrm {~A}$ . This coil lies on a horizontal table with the current flowing in the counterclockwise direction when viewed from above. At this point, the earth's magnetic field is $1.2 \times 10 ^ { - 5 } \mathrm {~T}$ directed $60 ^ { \circ }$ below the horizontal. What is the magnitude of the torque that the earth's magnetic field exerts on this loop?

A) $1.0 \times 10 ^ { - 5 } \mathrm {~N} \cdot \mathrm { m }$
B) $5.0 \times 10 ^ { - 6 } \mathrm {~N} \cdot \mathrm { m }$
C) $2.5 \times 10 ^ { - 6 } \mathrm {~N} \cdot \mathrm { m }$
D) $7.5 \times 10 ^ { - 6 } \mathrm {~N} \cdot \mathrm { m }$