29. Sources of Magnetic Field

A long, straight wire extends perpendicular to the plane of the screen. If the current in the wire is directed $\uparrow$ 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 $r$ from a long straight wire carrying a current $I$?

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?

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:

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 $I$. What is the magnitude of the magnetic field at a point $P$ located a distance $r$ from the wire?

Which of the following best describes the pattern of magnetic field lines around a long, straight current-carrying wire?