A magnet rests on a balance. A wire is supported independently with 0.040 m perpendicular to the magnetic field. Switching on a current of 2.0 A increases the balance reading by 3.2 g. Use g=10 N/kgg=10\ \mathrm{N/kg}g=10 N/kg and F=BIlF=BIlF=BIl. What is the magnetic flux density?
40 T40\ \mathrm{T}40 T
0.040 T0.040\ \mathrm{T}0.040 T
0.40 T0.40\ \mathrm{T}0.40 T
4.0 T4.0\ \mathrm{T}4.0 T