Q 84

Two long parallel wires are separated by 6.0 mm.The current in one of the wires is twice the other current.If the magnitude of the force on a 3.0-m length of one of the wires is equal to 8.0 N,what is the greater of the two currents?
A)0.20 A
B)0.40 A
C)40 mA
D)20 mA
E)0.63 A

Q 85

Two long parallel wires are separated by 2.0 cm.The current in one of the wires is three times the other current.If the magnitude of the force on a 2.0-m length of one of the wires is equal to 60 N,what is the greater of the two currents?
A)2.0 A
B)1.0 A
C)3.0 A
D)9.0 A
E)1.5 A

Q 86

Three long,straight,parallel wires all lie in the yz plane and each carries a current of 20 A in the positive z direction.The two outer wires are each 4.0 cm from the center wire.What is the magnitude of the magnetic force on a 50-cm length of either of the outer wires?
A)1.0 mN
B)0.50 mN
C)1.1 mN
D)1.5 mN
E)2.0 mN