Back(II) Two long parallel wires 8.20 cm apart carry 19.5-A dc currents in the same direction. Determine the magnetic field vector at a point P, 12.0 cm from one wire and 13.0 cm from the other. See Fig. 28–43. [Hint: Use the law of cosines. See Appendix A or inside rear cover.]
A long, straight wire extends perpendicular to the plane of the screen. If the current in the wire is directed out of the screen toward you, what is the direction of the magnetic field at a point to the right of the wire?
What is the magnitude of the magnetic field at a distance from a long straight wire carrying a current ?
A long straight wire carries a current vertically upward. Four compasses are placed at equal distances around the wire: one to the north, one to the south, one to the east, and one to the west of the wire. Which compass will point its needle directly east due to the magnetic field produced by the current?
A long horizontal wire carries a current of 42 A. A second wire, made of 1.00-mm-diameter copper wire and parallel to the first, is kept in suspension magnetically 5.0 cm below (Fig. 28–60). (a) Determine the magnitude and direction of the current in the lower wire. (b) Is the lower wire in stable equilibrium? (c) Repeat parts (a) and (b) if the second wire is suspended 5.0 cm above the first due to the first’s magnetic field.
Which of the following best describes the magnetic field produced around a long, straight wire carrying an electric current?
A vertical wire carries a current straight down. To the east of this wire, the magnetic field points:
(II) Two long straight wires each carry a dc current I out of the page toward the viewer, Fig. 28–38. Indicate, with appropriate arrows, the direction of at each of the points 1 to 6 in the plane of the page. State if the field is zero at any of the points.
Which of the following is the primary cause of the magnetic field surrounding a long, straight current-carrying wire?
A long, straight wire carries a current . What is the magnitude of the magnetic field at a point located a distance from the wire?
(II) A dc power line carries a current of 85 A west along the tops of 8.5-m-high poles. (a) What is the magnitude and direction of the magnetic field produced by this wire at the ground directly below? How does this compare with the Earth’s field of about ½G ? (b) Where would the current’s magnetic field cancel the Earth’s field?
Which of the following best describes the pattern of magnetic field lines around a long, straight current-carrying wire?
A continuous straight stream of protons passes a given point in space at a rate of 2.5 x 109 protons/s. What magnetic field do they produce 1.8 m from the beam?
Which of the following equations correctly gives the magnitude of the magnetic field at a distance of from a long straight wire carrying a current of if the field is measured to be ?