Question

1. ___ wrote the book on the lodestone and magnetic bodies, and on the great magnet the earth (de magnete).

charles de coulomb
pierre le pèlerin de maricourt
william gilbert
sir isaac newton

1. imaginary lines that indicate the direction and strength of a magnets magnetic field are called ___.

declination lines
isogonic lines
lines of flux
isoclinic lines

1. which of the following statements regarding permeability is not true?

a highly permeable substance will increase the force of attraction when placed between two magnets.
aluminum is a highly permeable substance.
a highly permeable substance can act as a magnetic shield.
the higher the permeability of a substance, the more easily it is magnetized.

1. magnetic resonance imaging produces three - dimensional images by detecting the ___ of a patients atoms when exposed to a powerful magnet.

electron spin
proton pairs
nucleus spin
number of neutrons

1. which of the following statements regarding domain theory is not true?

an object will have a magnetic field when most of its domains are lined up in the same direction.
a domain is a group of aligned atoms having a single magnetic field.
domains can be physically knocked out of alignment by striking the magnet.
a typical domain is about one centimeter across.

1. a permanent magnet will lose its magnetism when heated to its ___ point.

curie
coercivity
oersted
agonic

1. an electromagnet with twenty loops of wire has a strength of 100 n. how many loops of wire are needed for the strength to be 400 n?

10
40
80
100

1. the angle that a compass needle deviates from true north is called the angle of ___.

declination
deviation
deflection
induction

1. the angle of inclination (also called magnetic dip) is ( 0^{circ} ) at the ___.

north magnetic pole
south magnetic pole
agonic line
magnetic equator

1. the doughnut - shaped belts of high - speed charged particles that help protect the earth from the solar wind are called the ___.

auroras
magnetosphere
van allen radiation belts
coulomb radiation belts

Explanation:

1. William Gilbert wrote De Magnete. Charles de Coulomb is known for Coulomb's law in electrostatics. Pierre le Pèlerin de Maricourt made early studies on magnetism but not this book. Sir Isaac Newton is famous for laws of motion and gravitation.
2. Lines of flux (magnetic field lines) show direction and strength. Declination lines relate to magnetic declination. Isogonic lines are lines of equal magnetic declination. Isoclinic lines are lines of equal magnetic inclination.
3. Aluminum is not a highly permeable substance (it is a paramagnetic material with low permeability). A highly permeable substance increases attraction between magnets (like soft iron), can act as a shield, and higher permeability means easier magnetization.
4. MRI detects nucleus spin (specifically proton spin in hydrogen - rich tissues like water in the body). Electron spin is not the basis for MRI. Proton pairs is not the correct term. Number of neutrons is not relevant for MRI signal generation.
5. A typical domain is on the order of micrometers, not centimeters. When domains align, an object has a magnetic field. A domain is a group of aligned atoms. Striking a magnet can disrupt domain alignment.
6. The Curie point is the temperature at which a permanent magnet loses its magnetism. Coercivity is a measure of a material's resistance to demagnetization. Oersted is known for the discovery of electromagnetism. Agonic refers to a line (agonic line) where magnetic declination is zero.
7. For an electromagnet, assuming a linear relationship (if current is constant, strength is proportional to the number of loops). If \(N_1 = 20\) loops give \(F_1=100\space N\), and we want \(F_2 = 400\space N\). Using \(F=kN\) (where \(k\) is a constant), \(\frac{F_1}{N_1}=\frac{F_2}{N_2}\), \(N_2=\frac{F_2N_1}{F_1}=\frac{400\times20}{100}=80\).
8. The angle that a compass needle deviates from true north is the angle of declination. Deviation is related to local magnetic disturbances (e.g., on a ship). Deflection is a more general term. Induction is related to the creation of a magnetic field in a material.
9. The angle of inclination (magnetic dip) is \(0^{\circ}\) at the magnetic equator. At the north and south magnetic poles, the magnetic dip is \(90^{\circ}\). The agonic line is about magnetic declination.
10. The Van Allen radiation belts are doughnut - shaped belts of charged particles. Auroras are light displays. The magnetosphere is the region around a planet dominated by its magnetic field. Coulomb radiation belts is not a correct term.

Answer:

1. William Gilbert
2. lines of flux
3. Aluminum is a highly permeable substance.
4. nucleus spin
5. A typical domain is about one centimeter across.
6. Curie
7. 80
8. declination
9. magnetic equator
10. Van Allen radiation belts