29. Sources of Magnetic Field

A long straight wire carries a current upward. Point $A$ is located to the right of the wire. In which direction is the magnetic field at point $A$ due to the current in the wire?

When a coil of wire has an electric current $I$ passing through it, what effect does it have on a nearby magnet?

When a compass needle (whose north pole is the north-seeking end of a magnet) is allowed to rotate freely, to which of Earth's geographic poles does its $north pole$ point?

Which of the following statements best describes the significance of achieving a magnetic field of $37.2T$ at the MIT Francis Bitter Magnet Laboratory?

Current-carrying wires produce which kind of fields?

If the $Earth$ were completely solid and did not have a liquid outer core, how would this affect the generation and appearance of its magnetic field?

If two parallel wires carry electric currents in the same direction, how does this affect the magnetic field around the wires?

A compass needle’s magnetic north pole points toward which of the following?

What important role does the $\mathrm{magnetic} \mathrm{field}$ play for our planet?

A rectangular wire loop moves with constant velocity into a region where the right edge of the circuit enters a uniform magnetic field of magnitude $50mT$. If the magnetic field is directed into the page and the velocity of the loop is perpendicular to the field, what is the direction of the induced current in the loop as it enters the field?

How are magnetic field line models helpful in understanding the magnetic field produced by moving charges?

A thin ring of radius $R$ carries a total charge $Q$ and rotates with angular speed $\omega$ about its axis. What is the ring's magnetic dipole moment?

Which of the following correctly identifies the two poles of a magnet?

Which of the following electromagnets would produce the greatest magnetic field at the center of the coil ($B$)?

When a compass is used on $\mathrm{Earth}$, in which direction does the north magnetic side of the compass needle point?