$$\vec{B}_{\text{point charge}} = \frac{\mu_0$ q \vec{v} \times \hat{r}}{4\pi r^2$}$$

$$\vec{F} = q \vec{v} \times \vec{B}$$

Question 1

Which of the following statements best describes Gauss's Law for Magnetism?

Accepted Answer

It states that the net magnetic flux through any closed surface is always zero, implying there are no magnetic monopoles.

Question 2

A bar magnet is broken into three pieces. What happens to the magnetic poles of the resulting fragments?

Accepted Answer

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

Question 3

Which equation correctly represents the magnetic field produced by a moving point charge?

Accepted Answer

$$\vec{B}_{	ext{point charge}} = \frac{\mu_0$ q \vec{v} 	imes \hat{r}}{4\pi r^2$}$$

Question 4

A compass needle points north because:

Accepted Answer

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

Question 5

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

Accepted Answer

The magnetic field forms concentric circles around the wire, with direction given by the right-hand rule.

Question 6

What is the SI unit for magnetic field strength?

Accepted Answer

Tesla (T)

Question 7

If a current flows upward through a straight wire, what is the direction of the magnetic field at a point to the right of the wire?

Accepted Answer

Into the page

Question 8

Which formula gives the magnetic field at a distance $$r$$ from an infinite straight wire carrying current $$I$$?

Accepted Answer

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

Question 9

A charged particle moves perpendicular to a uniform magnetic field. What type of motion does it undergo?

Accepted Answer

Circular motion

Question 10

Which equation describes the force on a charge $$q$$ moving with velocity $$\vec{v} in a $$magnetic field $$\vec{B}$$?

Accepted Answer

$$\vec{F} = q \vec{v} 	imes \vec{B}$$

Question 11

If a proton and a deuteron (same charge, twice the mass) enter a uniform magnetic field with the same velocity, how do their trajectories compare?

Accepted Answer

The deuteron will have a larger radius of curvature than the proton.

Question 12

Which property of the cross product is essential for determining the direction of the magnetic field from a moving charge?

Accepted Answer

The cross product is perpendicular to both input vectors, with direction given by the right-hand rule.

Question 13

What happens to the magnetic field lines when iron filings are sprinkled around a bar magnet?

Accepted Answer

The filings align along the magnetic field lines, showing the direction and strength of the field.

Question 14

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

Accepted Answer

The magnetic field is always parallel to the electric field.

Question 15

A wire carries a current out of the page. What is the direction of the magnetic field at a point directly above the wire?

Accepted Answer

To the left

Question 16

Which of the following best explains why magnetic monopoles do not exist?

Accepted Answer

Gauss's Law for Magnetism states that the net magnetic flux through any closed surface is zero.

Question 17

A compass needle placed near a current-carrying wire will:

Accepted Answer

Align tangentially to a circle around the wire, indicating the direction of the magnetic field.

Question 18

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

Accepted Answer

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

Question 19

If a negative charge moves through a magnetic field, how does the direction of the force compare to that for a positive charge?

Accepted Answer

The force is in the opposite direction to that for a positive charge.

Magnetism and the Biot-Savart Law: Fundamentals and Applications

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