Unit 8: Magnetic Fields

Question 1

What did ancient mariners as compasses?

Answer 1

Magnetic rocks containing iron (lodestone).

Question 2

Two ends of a magnet behave very differently because magnets are __________; they have 2 opposite ends, called _____________

Answer 2

polar
poles

Question 3

the north pole is actually near where?

Answer 3

the earths south magnetic pole

Question 4

the earths south geographical poles is actually near where?

Answer 4

the earth’s north geographic

Question 5

what will a bar magnet do always when it is suspended and allowed to rotate freely

Answer 5

it will always align itself with the magnetic field of the earth

Question 6

no matter how small you break a magnet, what will it always have?

Answer 6

a north pole and a south pole

Question 7

law of magnetic poles

Answer 7

magnetic poles that have the same polarity will repel each other
magnetic poles that have opposite polarity will attract each other

Question 8

magnetization by contact

Answer 8

when a permanent bar magnet touches an object such as a nail, the bar polarizes the nail, making it a temporary magnet

Question 9

what do magnets attract?

Answer 9

other metals such as nails, paper clips, tacks, even though they are not polarized

Question 10

what metals are not attracted to metals

Answer 10

aluminium, copper, brass

Question 11

what metals are strongly attracted to magnets

Answer 11

iron, nickel, cobalt, and gadolinium

Question 12

what do you call materials that can become temporary magnets

Answer 12

ferromagnetic

Question 13

how do you permanently magnetize a nail or a screwdriver?

Answer 13

Rub it with a permanent magnet
Hit it with a hammer when the nail or screwdriver is aligned with the Earth’s magnetic field

Question 14

a group of neighbouring atoms whose poles are aligned

Answer 14

magnetic domain

Question 15

where do the domains point in a ferromagnetic material that is not magnetized

Answer 15

random directions

Question 16

where do the domains point in a ferromagnetic material that is magnetized

Answer 16

roughly the same direction

Question 17

no domains

Answer 17

non-magnetic material

Question 18

domains, but not lined up

Answer 18

magnetic material

Question 19

domains, and all are lined up

Answer 19

magnet

Question 20

why does the earth have a magnetic field

Answer 20

The core of the earth is a solid sphere composed mostly of iron and nickel. The magnetic domains of the earths core are aligned

Question 21

what is the earth composed mostly of?

Answer 21

iron and nickel

Question 22

World Magnetic Model

Answer 22

a program that helps your phone navigate. it improves the navigation of devices ranging from nuclear submarines to common smartphones

Question 23

Why is the WMM in trouble

Answer 23

the Earth’s magnetic field is changing

Question 24

How often is the World Magnetic Model updated

Answer 24

5 years

Question 25

Why was the WMM updated in 2019 rather than its scheduled update in 2020

Answer 25

Since late 2014, Earth’s core field has varied in an unpredicted and currently unpredicted manner

Question 26

long range magnetic forces can be interpreted as being what?

Answer 26

the result of magnetic fields

Question 27

what are magnetic fields

Answer 27

fields that exist in space where compass would experience a force

Question 28

a compass needle will naturally _ itself with ____________________________ unless a _____________ magnetic field is nearby which will _______ the direction it is pointing

Answer 28

align
the Earth’s magnetic field
stronger
alter

Question 29

what are magnetic field lines used for

Answer 29

to show the strength and direction of a magnetic field

Question 30

magnetic flux

Answer 30

the number of magnetic field lines passing through a surface perpendicular to the lines

Question 31

where is magnetic flux most concentrated

Answer 31

at the magnetic poles

Question 32

where is the magnetic field strength the highest

Answer 32

at the magnetic poles

Question 33

the direction of a magnetic field line is defined as the direction in which the _________ of a compass points when placed in a magnetic field

Answer 33

north pole

Question 34

where do magnetic field lines emerge from and enter

Answer 34

emerge from a magnet’s north seeking pole and enter at its south-seeking pole