Question 1

Which of the following best describes the pattern of the magnetic field around a long, straight current-carrying wire, as visualized by iron filings or compass needles?

Accepted Answer

The field lines form concentric circles centered on the wire.

Question 2

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 3

Which of the following materials is strongly attracted to a magnet due to its ferromagnetic properties?

Accepted Answer

Iron

Question 4

The Earth's geographic north pole is actually which type of magnetic pole?

Accepted Answer

A magnetic south pole

Question 5

A wire carries a current directly toward you. In what direction are the magnetic field lines surrounding the wire?

Accepted Answer

Counterclockwise

Question 6

Which right-hand rule is used to determine the direction of the magnetic field around a current-carrying wire?

Accepted Answer

Point your thumb in the direction of the current; your fingers curl in the direction of the magnetic field.

Question 7

What is the SI unit of magnetic field strength?

Accepted Answer

Tesla (T)

Question 8

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

Accepted Answer

A circular path

Question 9

Which equation gives the magnitude of the force on a straight wire of length $$l$$ carrying current $$I in a $$uniform magnetic field $$B at an $$angle $$	heta to $$the field?

Accepted Answer

$$F = IlB \sin 	heta$$

Question 10

A proton moves vertically upward in a region where the magnetic field points north. In which direction is the magnetic force on the proton?

Accepted Answer

West

Question 11

Which of the following statements about magnetic field lines is correct?

Accepted Answer

Magnetic field lines form closed loops.

Question 12

The force per unit length between two long, parallel wires carrying currents $$I_1$$ and $$I_2$$ separated by distance $$d is $$given by which equation?

Accepted Answer

$$\frac{F}{l} = \frac{\mu_0$ I_1$ I_2$}{2\pi d}$$

Question 13

A solenoid has $$N$$ turns, length $$l$$, and carries current $$I. $$What is the magnetic field inside the solenoid?

Accepted Answer

$$B = \mu_0$ N I / l$$

Question 14

Which device uses the force on a current-carrying coil in a magnetic field to produce rotational motion?

Accepted Answer

Electric motor

Question 15

In a mass spectrometer, ions of charge $$q$$ and velocity $$v$$ pass through perpendicular electric and magnetic fields such that $$qE = qvB. $$What is the velocity of ions that pass through undeflected?

Accepted Answer

$$v = E/B$$

Question 16

Which of the following is NOT a property of the force exerted by a magnetic field on a moving charge?

Accepted Answer

It can change the speed of the particle.

Question 17

A current-carrying wire is placed in a uniform magnetic field. The force on the wire is zero when:

Accepted Answer

The wire is parallel to the field.

Question 18

Which of the following best explains why a magnet can pick up unmagnetized iron objects like paper clips?

Accepted Answer

The magnet induces a temporary alignment of domains in the iron.

Question 19

What is the effect of increasing the number of turns per unit length in a solenoid, keeping the current constant?

Accepted Answer

The magnetic field inside the solenoid increases.

Question 20

Which of the following is a correct statement about the Hall effect?

Accepted Answer

It can be used to determine the sign of charge carriers in a conductor.

Magnetism: Magnetic Fields, Forces, and Applications

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