Question 1

Which of the following statements best explains why breaking a bar magnet in half does NOT produce isolated north or south poles?

Accepted Answer

Each fragment instantly becomes a new magnet with both a north and south pole.

Question 2

A compass needle points north because:

Accepted Answer

The north pole of the compass is attracted to the Earth's geographic north pole, which is actually a magnetic south pole.

Question 3

Which of the following is Gauss’s Law for Magnetism?

Accepted Answer

$$\displaystyle \oint \vec{B} \cdot d\vec{A} = 0$$

Question 4

The magnetic field at a distance $$r$$ from a long, straight current-carrying wire is given by:

Accepted Answer

$$\displaystyle B = \frac{\mu_0$ I}{2\pi r}$$

Question 5

A charged particle moves with velocity $$\vec{v}$$ perpendicular to a uniform magnetic field $$\vec{B}. $$What is the direction of the magnetic force on the particle?

Accepted Answer

Perpendicular to both $$\vec{v}$$ and $$\vec{B}$$, given by the right-hand rule.

Question 6

Which equation correctly gives the magnetic field at the center of a circular loop of radius $$R$$ carrying current $$I$$?

Accepted Answer

$$\displaystyle B = \frac{\mu_0$ I}{2R}$$

Question 7

A proton moves upward in a region where the magnetic field points out of the page. What is the direction of the magnetic force on the proton?

Accepted Answer

To the left

Question 8

Which of the following best describes the magnetic field lines around a bar magnet?

Accepted Answer

They emerge from the north pole and enter the south pole outside the magnet.

Question 9

A current $$I$$ flows upward in a long, straight wire. At a point to the right of the wire, what is the direction of the magnetic field?

Accepted Answer

Into the page

Question 10

Which of the following is a correct statement about the cross product $$\vec{A} 	imes \vec{B}$$?

Accepted Answer

It is a vector perpendicular to both $$\vec{A}$$ and $$\vec{B}$$, with magnitude $$AB \sin 	heta.$$

Question 11

A wire carries a current to the left. At a point above the wire, what is the direction of the magnetic field?

Accepted Answer

Out of the page

Question 12

Which of the following is NOT a property of the magnetic field $$\vec{B}$$?

Accepted Answer

It can be created by stationary electric charges.

Question 13

A charged particle moves in a circle of radius $$r in a $$uniform magnetic field $$B. $$Which equation relates the radius to the particle’s mass $$m$$, charge $$q$$, and speed $$v$$?

Accepted Answer

$$\displaystyle r = \frac{mv}{qB}$$

Question 14

Which of the following best explains why a magnet does not affect an electroscope?

Accepted Answer

Magnetic fields do not exert forces on stationary electric charges.

Question 15

The Biot-Savart Law for the magnetic field $$\vec{B}$$ due to a moving point charge is:

Accepted Answer

$$\displaystyle \vec{B} = \frac{\mu_0$}{4\pi} \frac{q\vec{v} 	imes \hat{r}}{r^2$}$$

Question 16

A deuteron (same charge as a proton, but twice the mass) enters a uniform magnetic field with the same velocity as a proton. Compared to the proton, the deuteron’s circular path will have:

Accepted Answer

Twice the radius

Question 17

Which of the following is a consequence of Gauss’s Law for Magnetism?

Accepted Answer

Magnetic monopoles do not exist.

Question 18

A bar magnet is brought near a compass. The north pole of the compass needle is attracted to which part of the bar magnet?

Accepted Answer

The south pole

Question 19

Which of the following best describes the effect of a magnetic field on a stationary electron?

Accepted Answer

There is no force exerted on the electron.

Magnetism and the Biot-Savart Law: Foundations and Applications

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