Q: Which equation correctly expresses the magnitude of the magnetic force $$F on a $$charge $$q$$ moving with velocity $$\vec{v} in a $$magnetic field $$\vec{B}$$?

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

Question 1

Which of the following statements best describes the difference between magnetic poles and electric charges?

Accepted Answer

Magnetic poles always exist in pairs, while electric charges can exist independently as positive or negative charges.

Question 2

A straight current-carrying wire produces a magnetic field. What is the direction of the magnetic field at a point directly above the wire if the current flows to the right?

Accepted Answer

Out of the page

Question 3

Which equation correctly expresses the magnitude of the magnetic force $$F on a $$charge $$q$$ moving with velocity $$\vec{v} in a $$magnetic field $$\vec{B}$$?

Accepted Answer

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

Question 4

If a compass is placed near a current-carrying wire, what will happen to the compass needle?

Accepted Answer

It will align with the magnetic field produced by the wire.

Question 5

Which of the following best explains why the earth acts as a giant magnet?

Accepted Answer

The movement of molten iron in the earth's outer core generates a magnetic field.

Question 6

A bar magnet is cut in half. What happens to the magnetic poles?

Accepted Answer

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

Question 7

Which of the following is a correct statement about magnetic dipoles?

Accepted Answer

A magnetic dipole consists of a north and a south pole separated by a distance.

Question 8

A charged particle moves perpendicular to a uniform magnetic field. What is the path of the particle?

Accepted Answer

It moves in a circular path.

Question 9

Which of the following materials is most likely to be ferromagnetic?

Accepted Answer

Iron

Question 10

The magnetic field lines around a straight current-carrying wire form which shape?

Accepted Answer

Concentric circles around the wire

Question 11

A proton moves with velocity $$\vec{v} in a $$region with a uniform magnetic field $$\vec{B}. If$$ $$\vec{v} is $$parallel to $$\vec{B}$$, what is the magnetic force on the proton?

Accepted Answer

Zero

Question 12

Which of the following best describes the role of the magnetic field in the aurora borealis phenomenon?

Accepted Answer

It guides charged particles from the solar wind along field lines into the upper atmosphere.

Question 13

Which experiment would best demonstrate the existence of a magnetic field around a current-carrying wire?

Accepted Answer

Placing a compass near the wire and observing its deflection.

Question 14

If the current in a wire is doubled, what happens to the strength of the magnetic field at a fixed distance from the wire?

Accepted Answer

It is doubled.

Question 15

Which of the following is true about the direction of the magnetic field produced by a current-carrying wire?

Accepted Answer

It depends on the direction of the current.

Question 16

A student wants to increase the magnetic field strength inside a solenoid. Which action will be most effective?

Accepted Answer

Increase the number of turns of wire.

Question 17

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

Accepted Answer

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

Question 18

A wire carries a current of $$5\ \mathrm{A}$$ and produces a magnetic field at a distance of $$0.1\ \mathrm{m}. $$What is the magnitude of the magnetic field at that point? (Use $$\mu_0$ = 4\pi 	imes 10$$^{-7}$$\ \mathrm{T\cdot m/A})$$

Accepted Answer

$$1 	imes 10$$^{-6}$$\ \mathrm{T}$$

Question 19

A charged particle moves in a magnetic field and experiences a force. Which of the following changes will increase the magnitude of the force?

Accepted Answer

Increase the charge of the particle.

Question 20

Which of the following is NOT a property of magnetic field lines?

Accepted Answer

They originate from electric charges.

Magnetism and the Magnetic Field: Fundamental Concepts and Applications

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