24.1

24.2

24.3

Magnetic Poles Magnetic Field

24.4

Magnetic FieldTorque

24.5

Induced magnetism

24.6

24.7

24.8

Galvanometer Volt-meter

24.9

24.10

Earth’s Magnetic Field

Convection currents Aurora Borealis – Charged particles

24.11

Mars (magfield) ~ 1/800 Earth (magfield)

24.12

-- Questions --

MULTIPLE CHOICE.

Choose the one alternative that best completes the statement or

answers the question.

24.13

1) An electron is shot from the right, toward a spot just between the ends of the magnet. The electron

A) accelerates straight toward the spot. B) is attracted to one of the poles, and repelled from the other. C) is deflected into the plane of the page. D) is repelled by both poles, and therefore is turned back. E) is unaffected by the field.

2) Magnetic domains normally occur in A) copper. B) iron. C) silver. D) all of these. E) none of these.

24.14

3) Compared to the huge force that attracts an iron tack to a strong magnet, the force that the tack exerts on the magnet is A) equally huge. B) relatively small. C) more information is needed.

4) Which pole of a compass needle points to a south pole of a magnet? A) north pole B) south pole C) both of these

24.15

5) The force on an electron moving in a magnetic field will be the largest when its direction is

A) exactly opposite to the magnetic field direction. B) the same as the magnetic field direction. C) perpendicular to the magnetic field direction. D) at an angle other than 90 degrees to the magnetic field direction. E) none of these.

6) If a steady magnetic field exerts a force on a moving charge, that force is directed

A) at right angles to the direction of the field. B) opposite the direction of the field. C) in the direction of the field.

24.16

7) The source of all magnetism is A) moving electric charge. B) tiny pieces of iron. C) tiny domains of aligned atoms. D) ferromagnetic materials. E) none of these.

8) Magnetism is due to the motion of electrons as they A) move around the nucleus. B) spin on their axes. C) both of these. D) none of these.

24.17

9) The intensity of cosmic rays bombarding the Earth's surface is largest at the A) mid-latitudes. B) poles. C) equator.

10) If we think of the Earth as a magnet, its north (-seeking) pole is nearest A) the Hudson Bay region of Canada. B) Australia. C) both of these.

24.18

11) If a compass is moved from the northern hemisphere to the southern hemisphere, its magnetic needle will change direction

A) by 180 degrees. B) depending on where the measurement is taken. C) hardly at all. D) by 90 degrees. E) none of these

12) A possible cause for the existence of the Earth's magnetic field is A) great numbers of very slow moving charges in the Earth. B) moving charges in the liquid part of the Earth's core. C) convection currents in the liquid part of the Earth's core. D) all of these. E) none of these.

24.19

13) An iron rod becomes magnetic when A) positive ions accumulate at one end and negative ions at the other

end. B) its electrons stop moving and point in the same direction. C) its atoms are aligned having plus charges on one side and negative

charges on the other. D) the net spins of its electrons are in the same direction. E) none of these.

14) Magnetic field lines about a current-carrying wire A) circle the wire in closed loops. B) extend radially from the wire. C) both of these. D) neither of these.

24.20

15) Surrounding every moving electron is A) a magnetic field. B) an electric field. C) both of these. D) none of these.

16) Pigeons navigate primarily by A) a keen sense of smell. B) a good memory. C) magnetic sensors in their heads. D) ultra-high-pitched sounds. E) none of these.

24.21

-- Answers --

MULTIPLE CHOICE.

The one alternative that best completes the statement or

answers the question.

24.22

Chapter 24

1) Answer: C 2) Answer: B 3) Answer: A 4) Answer: A 5) Answer: C 6) Answer: A 7) Answer: A 8) Answer: C 9) Answer: B 10) Answer: B 11) Answer: C 12) Answer: D 13) Answer: D 14) Answer: A 15) Answer: C 16) Answer: C