A magnetic dipole is under the influence of two magnetic fields. The angle between the field directions is 60°, and one of the fields has a magnitude of 1.2 × 10–2 T. If the dipole comes to stable equilibrium at an angle of 15° with this field, what is the magnitude of the other field?
Let us first decide the directions which can best represent the situation. Here, BH=Bcosδ =0.39×cos35oG BH=0.32G and BV=Bsinδ=0.39×sin35oG BV=0.22G Telephone cable carry a total current of 4.0A in direction east to west. We want resultant magnetic field 4.0cm below. Bwire=4πμor2I=10−7×4×10−22×4 =2×10−5T=0.2G=0.2G Net magnetic field Bnet=(BH−Bwire)2+BV2 Bnet=(0.12)2+(0.22)2=0.0144+0.0484=0.25G
