Two long straight parallel wires separated by a distance of 20 cm carry currents of 30 A and 40 A in opposite directions. What is the magnitude of the resulting magnetic field at a point that is 15 cm from the wire carrying the 30-A current and 25 cm from the other wire?
a. 51 T
b. 33 T
c. 72 T
d. 64 T
e. 46 T
[Ques. 2] Each of two long straight parallel wires separated by a distance of 16 cm carries a current of 20 A in the same direction. What is the magnitude of the resulting magnetic field at a point that is 10 cm from each wire?
a. 57 T
b. 80 T
c. 64 T
d. 48 T
e. 40 T
[Ques. 3] A 2.0-cm length of wire centered on the origin carries a 20-A current directed in the positive y direction. Determine the magnetic field at the point x = 5.0 m on the x-axis.
a. 1.6 nT in the negative z direction
b. 1.6 nT in the positive z direction
c. 2.4 nT in the negative z direction
d. 2.4 nT in the negative z direction
e. None of the above
[Ques. 4] Two long parallel wires each carry a current of 5.0 A directed to the east. The two wires are separated by 8.0 cm. What is the magnitude of the magnetic field at a point that is 5.0 cm from each of the wires?
a. 72 T
b. 48 T
c. 24 T
d. 96 T
e. 32 T
[Ques. 5] One long wire carries a current of 30 A along the entire x axis. A second long wire carries a current of 40 A perpendicular to the xy plane and passes through the point (0, 4, 0) m. What is the magnitude of the resulting magnetic field at the point y = 2.0 m on the y axis?
a. 4.0 T
b. 5.0 T
c. 3.0 T
d. 7.0 T
e. 1.0 T
[Ques. 6] Two wires, each having a weight per unit length of 1.0 104 N/m, are strung parallel, one 0.10 m above the other. If the wires carry the same current, though in opposite directions, how great must the current in each wire be for the magnetic field of the lower conductor to balance the weight of the upper conductor?
[Ques. 7] When a ferromagnetic material that has been magnetized is brought to a temperature greater than the Curie temperature, what happens to its residual magnetism?
a. Nothing happens to the residual magnetism.
b. The residual magnetism disappears.
c. The residual magnetism reaches it's highest value.
d. All the magnetic domains causing magnetism become a single domain.
e. The material of the magnet melts causing currents that are magnetic.
[Ques. 8] On the average, in a ferromagnetic domain permanent atomic magnetic moments are aligned ____ to one another.
a. antiparallel
b. parallel
c. perpendicular
d. alternately parallel and antiparallel
e. randomly relative
[Ques. 9] The magnetic dipole moment of an electron (charge = e; mass = me) moving in a circular orbit of radius r with speed v about a nucleus of mass mN is proportional to
a. r.
b. v.
c. vr.
d. evr.
e. mNvr.
[Ques. 10] A stream of electrons passes through a velocity filter where the crossed magnetic and electric fields are 0.020 T and 5.00 104 V/m, respectively. Find the kinetic energy (in electron volts) of the electrons passing through the filter. 1 eV = 1.60 1019 J
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