28. Magnetic Fields and Forces

Which of the following statements about the direction of the $B$ field (magnetic field) around a straight, current-carrying wire is correct?

Which of the following is the primary source of magnetic fields $B$?

In devices that use electromagnets, why is a permanent magnet often included as well?

Which of the following components are typically found in the magnetic system of a magneto?

How can magnets attract or repel each other without touching?

In the context of Earth's magnetic field, what is one end of a magnetized compass's needle attracted to?

In a typical bar magnet, where is the magnetic force the strongest?

If you bring the $\mathrm{north} \mathrm{pole}$ of one bar magnet close to the $\mathrm{north} \mathrm{pole}$ of another bar magnet, will these magnets be attracted or repelled?

A bar magnet is placed near the end of a solenoid with its north pole facing the solenoid's south pole. When current flows through the solenoid to create a south magnetic pole at the end closest to the bar magnet, what is the direction of the magnetic force that the solenoid exerts on the bar magnet?

A long straight wire carries a current of $I$. What is the magnetic field strength at point 1, located a distance $r$ from the wire?

Which statement best describes the magnetic field of Jupiter compared to Earth's magnetic field?

Which of the following devices operates using magnetism rather than electromagnetic radiation?