1) Jumper cables used to start a stalled vehicle oen carry a70-A current. How strong is the magnetic field 5.0 cm from onecable? Compare to the Earth’s magnetic field (5.0 × 10−5 T).
2) A power line carries a current of 100 A west along the topsof 10-m-high poles. (a) What is the magnitude and direction of themagnetic field produced by this wire at the ground directly below?How does this compare with the Earth’s magnetic eld of about 1 2 G?(b) Where would the wire’s magnetic field cancel the Earth’sfield?
